1.19.4 RB 4

https://forums.minecraftforge.net/topic/154386-forge-454-minecraft-1194/

.github/support.yml

@@ -1,16 +0,0 @@
-# Configuration for support-requests - https://github.com/dessant/support-requests
-
-# Label used to mark issues as support requests
-supportLabel: Forum
-# Comment to post on issues marked as support requests. Add a link
-# to a support page, or set to `false` to disable
-supportComment: >
-  👋 We use the issue tracker exclusively for final bug reports and feature requests.
-  However, this issue appears to be better suited for the
-  [Forge Support Forums](http://www.minecraftforge.net/forum/forum/18-support-bug-reports/).
-  Please create a new topic on the support forum with this issue, and the conversation can
-  continue there.
-# Whether to close issues marked as support requests
-close: true
-# Whether to lock issues marked as support requests
-lock: true

.github/workflows/comments.yml

@@ -0,0 +1,16 @@
+name: 'Comment actions'
+
+on: issue_comment
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  discussions: write
+
+jobs:
+  labels:
+    uses: MinecraftForge/SharedActions/.github/workflows/comment_actions.yml@main
+    secrets:
+      GH_APP_KEY: ${{ secrets.GH_APP_KEY }}
+      GH_APP_NAME: ${{ secrets.GH_APP_NAME }}

.github/workflows/issues.yml

@@ -0,0 +1,16 @@
+name: 'Issue actions'
+
+on: issues
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  discussions: write
+
+jobs:
+  labels:
+    uses: MinecraftForge/SharedActions/.github/workflows/issue_actions.yml@main
+    secrets:
+      GH_APP_KEY: ${{ secrets.GH_APP_KEY }}
+      GH_APP_NAME: ${{ secrets.GH_APP_NAME }}

.github/workflows/pull_request_review.yml

@@ -0,0 +1,13 @@
+name: 'PR Review'
+
+on: pull_request_review
+
+jobs:
+  upload_payload:
+    name: Upload payload
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/upload-artifact@v3 # Payload artifact is consumed in Actionable
+        with:
+          name: payload
+          path: ${{ github.event_path }}

.github/workflows/pull_request_review_comment.yml

@@ -0,0 +1,13 @@
+name: 'PR Review Comment'
+
+on: pull_request_review_comment
+
+jobs:
+  upload_payload:
+    name: Upload payload
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/upload-artifact@v3 # Payload artifact is consumed in Actionable
+        with:
+          name: payload
+          path: ${{ github.event_path }}

.github/workflows/pull_request_review_comment_run.yml

@@ -0,0 +1,20 @@
+name: 'Pull Request Review Comment actions'
+
+on:
+  workflow_run:
+    workflows: [PR Review Comment]
+    types:
+      - completed
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  discussions: write
+
+jobs:
+  labels:
+    uses: MinecraftForge/SharedActions/.github/workflows/pr_review_comment_actions.yml@main
+    secrets:
+      GH_APP_KEY: ${{ secrets.GH_APP_KEY }}
+      GH_APP_NAME: ${{ secrets.GH_APP_NAME }}

.github/workflows/pull_request_review_run.yml

@@ -0,0 +1,20 @@
+name: 'Pull Request Review actions'
+
+on:
+  workflow_run:
+    workflows: [PR Review]
+    types:
+      - completed
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  discussions: write
+
+jobs:
+  labels:
+    uses: MinecraftForge/SharedActions/.github/workflows/pr_review_actions.yml@main
+    secrets:
+      GH_APP_KEY: ${{ secrets.GH_APP_KEY }}
+      GH_APP_NAME: ${{ secrets.GH_APP_NAME }}

.github/workflows/pull_requests.yml

@@ -0,0 +1,18 @@
+name: 'Pull Request actions'
+
+on:
+  pull_request_target:
+    types: [assigned, unassigned, labeled, unlabeled, opened, edited, closed, reopened, synchronize, converted_to_draft, ready_for_review, locked, unlocked, review_requested, review_request_removed, auto_merge_enabled, auto_merge_disabled]
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  discussions: write
+
+jobs:
+  labels:
+    uses: MinecraftForge/SharedActions/.github/workflows/pr_actions.yml@main
+    secrets:
+      GH_APP_KEY: ${{ secrets.GH_APP_KEY }}
+      GH_APP_NAME: ${{ secrets.GH_APP_NAME }}

.github/workflows/push.yml

@@ -0,0 +1,16 @@
+name: 'Push actions'
+
+on: push
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  discussions: write
+
+jobs:
+  labels:
+    uses: MinecraftForge/SharedActions/.github/workflows/push_actions.yml@main
+    secrets:
+      GH_APP_KEY: ${{ secrets.GH_APP_KEY }}
+      GH_APP_NAME: ${{ secrets.GH_APP_NAME }}

.gitignore

@@ -33,6 +33,8 @@
 /projects/**/*.launch
 /repo/
 src/generated/resources/.cache/
+src/generated_test/resources/.cache/
+src/generated_mdk/resources/.cache/
 
 #Patch rejects
 /patches-/

.teamcity/settings.kts

@@ -1,5 +1,7 @@
 import jetbrains.buildServer.configs.kotlin.v2019_2.*
 import jetbrains.buildServer.configs.kotlin.v2019_2.projectFeatures.githubIssues
+import jetbrains.buildServer.configs.kotlin.*
+import jetbrains.buildServer.configs.kotlin.v2019_2.buildSteps.gradle
 
 /*
 The settings script is an entry point for defining a TeamCity
@@ -30,11 +32,13 @@ project {
     buildType(Build)
     buildType(BuildSecondaryBranches)
     buildType(PullRequests)
+    buildType(PullRequestChecks)
+    buildType(PullRequestCompatibility)
 
     params {
-        text("docker_jdk_version", "17", label = "Gradle version", description = "The version of the JDK to use during execution of tasks in a JDK.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
-        text("docker_gradle_version", "7.4", label = "Gradle version", description = "The version of Gradle to use during execution of Gradle tasks.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
-        text("git_main_branch", "1.18.x", label = "Git Main Branch", description = "The git main or default branch to use in VCS operations.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
+        text("docker_jdk_version", "21", label = "Gradle version", description = "The version of the JDK to use during execution of tasks in a JDK.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
+        text("docker_gradle_version", "8.8", label = "Gradle version", description = "The version of Gradle to use during execution of Gradle tasks.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
+        text("git_main_branch", "1.20.x", label = "Git Main Branch", description = "The git main or default branch to use in VCS operations.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
         text("git_branch_spec", """
                 +:refs/heads/(main*)
                 +:refs/heads/(master*)
@@ -134,3 +138,71 @@ object PullRequests : BuildType({
         """.trimIndent()
     }
 })
+
+object PullRequestChecks : BuildType({
+    templates(AbsoluteId("MinecraftForge_BuildPullRequests"), AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"))
+    id("MinecraftForge_MinecraftForge__PullRequestChecks")
+    name = "Pull Requests (Checks)"
+    description = "Checks pull requests for the project"
+
+    steps {
+        gradle {
+            name = "Check"
+            id = "RUNNER_10_Check"
+
+            tasks = "checkAll"
+            gradleParams = "--continue %gradle_custom_args%"
+            enableStacktrace = true
+            dockerImage = "%docker_gradle_image%"
+            dockerRunParameters = """
+                -v "/opt/cache/agent/gradle:/home/gradle/.gradle"
+                -v "/opt/cache/shared/gradle:/home/gradle/rocache:ro"
+                --network=host
+                -u 1000:1000
+                %docker_additional_args%
+            """.trimIndent()
+        }
+    }
+
+    vcs {
+        branchFilter = """
+            +:*
+            -:1.*
+            -:<default>
+        """.trimIndent()
+    }
+})
+
+object PullRequestCompatibility : BuildType({
+    templates(AbsoluteId("MinecraftForge_BuildPullRequests"), AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"))
+    id("MinecraftForge_MinecraftForge__PullRequestCompatibility")
+    name = "Pull Requests (Compatibility)"
+    description = "Validates binary compatibility for pull requests made to the project"
+
+    steps {
+        gradle {
+            name = "Validate"
+            id = "RUNNER_10_Compatibility"
+
+            tasks = "checkJarCompatibility"
+            gradleParams = "--continue %gradle_custom_args%"
+            enableStacktrace = true
+            dockerImage = "%docker_gradle_image%"
+            dockerRunParameters = """
+                -v "/opt/cache/agent/gradle:/home/gradle/.gradle"
+                -v "/opt/cache/shared/gradle:/home/gradle/rocache:ro"
+                --network=host
+                -u 1000:1000
+                %docker_additional_args%
+            """.trimIndent()
+        }
+    }
+
+    vcs {
+        branchFilter = """
+            +:*
+            -:1.*
+            -:<default>
+        """.trimIndent()
+    }
+})

Jenkinsfile

@@ -1,125 +0,0 @@
-@Library('forge-shared-library')_
-
-pipeline {
-    options {
-        disableConcurrentBuilds()
-    }
-    agent {
-        docker {
-            image 'gradle:7-jdk16'
-            //args '-v forgegc:/home/gradle/.gradle_cache/'
-        }
-    }
-    environment {
-        GRADLE_ARGS = '--no-daemon --console=plain' // No daemon for now as FG3 kinda derps. //'-Dorg.gradle.daemon.idletimeout=5000'
-        DISCORD_WEBHOOK = credentials('forge-discord-jenkins-webhook')
-        DISCORD_PREFIX = "Job: Forge Branch: ${BRANCH_NAME} Build: #${BUILD_NUMBER}"
-        JENKINS_HEAD = 'https://wiki.jenkins-ci.org/download/attachments/2916393/headshot.png'
-    }
-
-    stages {
-        stage('notify_start') {
-            when {
-                not {
-                    changeRequest()
-                }
-            }
-            steps {
-                discordSend(
-                    title: "${DISCORD_PREFIX} Started",
-                    successful: true,
-                    result: 'ABORTED', //White border
-                    thumbnail: JENKINS_HEAD,
-                    webhookURL: DISCORD_WEBHOOK
-                )
-            }
-        }
-        /*
-        stage('pull_cache') {
-            steps {
-                sh 'cp -r /home/gradle/.gradle_cache/jdks/ /home/gradle/.gradle/jdks/'
-                sh 'cp -r /home/gradle/.gradle_cache/wrapper/ /home/gradle/.gradle/wrapper/'
-                sh 'cp -r /home/gradle/.gradle_cache/caches/ /home/gradle/.gradle/caches/'
-            }
-        }
-        */
-        stage('setup') {
-            steps {
-                withGradle {
-                    sh './gradlew ${GRADLE_ARGS} --refresh-dependencies --continue setup'
-                }
-                script {
-                    env.MYVERSION = sh(returnStdout: true, script: './gradlew :forge:properties -q | grep "^version:" | cut -d" " -f2').trim()
-                    env.FMLONLY_VERSION = sh(returnStdout: true, script: './gradlew :fmlonly:properties -q | grep "^version:" | cut -d" " -f2').trim()
-                }
-            }
-        }
-        stage('changelog') {
-            when {
-                not {
-                    changeRequest()
-                }
-            }
-            steps {
-                writeChangelog(currentBuild, 'build/changelog.txt')
-            }
-        }
-        stage('publish') {
-            when {
-                not {
-                    changeRequest()
-                }
-            }
-            environment {
-                CROWDIN = credentials('forge-crowdin')
-                KEYSTORE = credentials('forge-jenkins-keystore-old')
-                KEYSTORE_KEYPASS = credentials('forge-jenkins-keystore-old-keypass')
-                KEYSTORE_STOREPASS = credentials('forge-jenkins-keystore-old-keypass')
-            }
-            steps {
-                withCredentials([usernamePassword(credentialsId: 'maven-forge-user', usernameVariable: 'MAVEN_USER', passwordVariable: 'MAVEN_PASSWORD')]) {
-                    withGradle {
-                        sh './gradlew ${GRADLE_ARGS} publish -PkeystoreKeyPass=${KEYSTORE_KEYPASS} -PkeystoreStorePass=${KEYSTORE_STOREPASS} -Pkeystore=${KEYSTORE} -PcrowdinKey=${CROWDIN}'
-                    }
-                }
-            }
-            post {
-                success {
-                    build job: 'filegenerator', parameters: [string(name: 'COMMAND', value: "promote net.minecraftforge:forge ${env.MYVERSION} latest")], propagate: false, wait: false
-                    build job: 'filegenerator', parameters: [string(name: 'COMMAND', value: "promote net.minecraftforge:fmlonly ${env.FMLONLY_VERSION} latest")], propagate: false, wait: false
-                }
-            }
-        }
-        stage('test_publish_pr') { //Publish to local repo to test full process, but don't include credentials so it can't sign/publish to maven
-            when {
-                changeRequest()
-            }
-            environment {
-                CROWDIN = credentials('forge-crowdin')
-            }
-            steps {
-                withGradle {
-                    sh './gradlew ${GRADLE_ARGS} publish -PcrowdinKey=${CROWDIN}'
-                }
-            }
-        }
-    }
-    post {
-        always {
-            script {
-                archiveArtifacts artifacts: 'projects/forge/build/libs/**/*.*', fingerprint: true, onlyIfSuccessful: true, allowEmptyArchive: true
-
-                if (env.CHANGE_ID == null) { // This is unset for non-PRs
-                    discordSend(
-                        title: "${DISCORD_PREFIX} Finished ${currentBuild.currentResult}",
-                        description: '```\n' + getChanges(currentBuild) + '\n```',
-                        successful: currentBuild.resultIsBetterOrEqualTo("SUCCESS"),
-                        result: currentBuild.currentResult,
-                        thumbnail: JENKINS_HEAD,
-                        webhookURL: DISCORD_WEBHOOK
-                    )
-                }
-            }
-        }
-    }
-}

build.gradle

@@ -1,15 +1,11 @@
-buildscript {
-    repositories {
-        mavenLocal()
-        maven { url = 'https://maven.minecraftforge.net/' }
-        mavenCentral()
-    }
-    dependencies {
-        classpath 'net.minecraftforge.gradle:ForgeGradle:[5.1.39,)'
-    }
-}
-
+import de.undercouch.gradle.tasks.download.Download
 import groovy.json.JsonBuilder
+import net.minecraftforge.forge.tasks.checks.CheckATs
+import net.minecraftforge.forge.tasks.checks.CheckExcs
+import net.minecraftforge.forge.tasks.checks.CheckPatches
+import net.minecraftforge.forge.tasks.checks.CheckSAS
+import net.minecraftforge.forge.tasks.checks.CheckTask
+import net.minecraftforge.forge.tasks.checks.CheckMode
 
 import java.nio.file.Files
 import java.util.Date
@@ -24,13 +20,17 @@ import net.minecraftforge.gradle.common.tasks.SignJar
 import net.minecraftforge.gradle.userdev.tasks.RenameJar
 import org.apache.tools.ant.filters.ReplaceTokens
 import org.gradle.plugins.ide.eclipse.model.SourceFolder
+import org.objectweb.asm.Opcodes
 
 plugins {
     id 'org.cadixdev.licenser' version '0.6.1'
-    id 'com.github.ben-manes.versions' version '0.36.0'
-    id 'net.minecraftforge.gradleutils' version '2.+'
+    id 'com.github.ben-manes.versions' version '0.46.0'
+    id 'net.minecraftforge.gradleutils' version '[2.2,2.3)'
     id 'eclipse'
-    id 'de.undercouch.download' version '4.1.2'
+    id 'idea'
+    id 'de.undercouch.download' version '5.4.0'
+    id 'net.minecraftforge.gradle.patcher' version '[6.0,6.2)' apply false
+    id 'net.minecraftforge.gradle.mcp' version '[6.0,6.2)' apply false
 }
 
 Util.init() //Init all our extension methods!
@@ -45,32 +45,48 @@ ext {
         ]
     }
     MAPPING_CHANNEL = 'official'
-    MAPPING_VERSION = '1.18.2'
-    MC_VERSION = '1.18.2'
-    MCP_VERSION = '20220404.173914'
-    SPI_VERSION = '4.0.10'
+    MAPPING_VERSION = '1.19.4'
+    MC_VERSION = '1.19.4'
+    MC_NEXT_VERSION = '1.20'
+    MCP_VERSION = '20230314.122934'
+    SPI_VERSION = '6.0.0'
     ACCESSTRANSFORMERS_VERSION = '8.0.4'
-    COREMODS_VERSION = '5.0.1'
-    EVENTBUS_VERSION = '5.0.3'
-    MODLAUNCHER_VERSION = '9.1.3'
-    SECUREJARHANDLER_VERSION = '1.0.3'
-    BOOTSTRAPLAUNCHER_VERSION = '1.0.0'
-    ASM_VERSION = '9.2'
-    INSTALLER_VERSION = '2.1.+'
+    COREMODS_VERSION = '5.2.4'
+    EVENTBUS_VERSION = '6.0.3'
+    MODLAUNCHER_VERSION = '10.0.8'
+    SECUREJARHANDLER_VERSION = '2.1.6'
+    BOOTSTRAPLAUNCHER_VERSION = '1.1.2'
+    ASM_VERSION = '9.7.1'
+    INSTALLER_VERSION = '2.2.+'
     MIXIN_VERSION = '0.8.5'
+    TERMINALCONSOLEAPPENDER_VERSION = '1.2.0'
+    JLINE_VERSION = '3.12.+'
+    NIGHTCONFIG_VERSION = '3.6.4'
+    JETBRAINS_ANNOTATIONS_VERSION = '23.0.0'
+    SLF4J_API_VERSION = '1.8.0-beta4'
+    APACHE_MAVEN_ARTIFACT_VERSION = '3.8.5'
+    JARJAR_VERSION = '0.3.19'
+
+    // These versions should be kept in sync with the version manifest JSON
+    // To use a version newer than the version manifest JSON, the dependency must be added to the installer configuration
+    MOJANG_LOGGING_VERSION = '1.1.1'
+    LOG4J_VERSION = '2.19.0'
+    GUAVA_VERSION = '31.1-jre'
+    GSON_VERSION = '2.10'
+    APACHE_COMMONS_LANG3_VERSION = '3.12.0'
+    JOPT_SIMPLE_VERSION = '5.0.4'
+    COMMONS_IO_VERSION = '2.11.0'
 
     GIT_INFO = gradleutils.gitInfo
     VERSION = gradleutils.getFilteredMCTagOffsetBranchVersion(true, '[0-9]', MC_VERSION)
     // FML_VERSION = gradleutils.getFilteredMCTagOffsetBranchVersion(true, 'FML', MC_VERSION)
     FORGE_VERSION = VERSION.substring(MC_VERSION.length() + 1)
 
-    SPECIAL_SOURCE = 'net.md-5:SpecialSource:1.10.0'
-    BINPATCH_TOOL = 'net.minecraftforge:binarypatcher:1.0.12:fatjar'
-    INSTALLER_TOOLS = 'net.minecraftforge:installertools:1.3.0'
+    BINPATCH_TOOL = 'net.minecraftforge:binarypatcher:1.1.1:fatjar'
+    INSTALLER_TOOLS = 'net.minecraftforge:installertools:1.4.1'
     JAR_SPLITTER = 'net.minecraftforge:jarsplitter:1.1.4'
     FART = 'net.minecraftforge:ForgeAutoRenamingTool:0.1.22:all'
-    MIN_TAG_FOR_CHANGELOG = "39.0"
-    LAST_RB = GIT_INFO.tag.rsplit('.', 1)[1] as int >= 1 ? GIT_INFO.tag + '.0' : null
+    MIN_TAG_FOR_CHANGELOG = '41.0'
 }
 
 println('Version: ' + VERSION +
@@ -88,8 +104,8 @@ def extraTxts = [
     rootProject.tasks.createChangelog.outputFile
 ]
 
-task downloadVersionManifest(type: Download) {
-    src 'https://launchermeta.mojang.com/mc/game/version_manifest_v2.json'
+tasks.register('downloadVersionManifest', Download) {
+    src 'https://piston-meta.mojang.com/mc/game/version_manifest_v2.json'
     dest file('build/versions/version_manifest.json')
     useETag 'all'
     onlyIfModified true
@@ -138,6 +154,10 @@ subprojects {
             name = 'forge'
             url = 'https://maven.minecraftforge.net/'
         }
+        maven {
+            name = 'minecraft'
+            url = 'https://libraries.minecraft.net/'
+        }
     }
 
     java.toolchain.languageVersion = JavaLanguageVersion.of(17)
@@ -199,45 +219,47 @@ project(':mcp') {
     }
 }
 
-project(':clean') {
-    evaluationDependsOn(':mcp')
-    apply plugin: 'net.minecraftforge.gradle.patcher'
-    tasks.withType(AbstractPublishToMaven.class).forEach{tsk -> tsk.enabled = false } // We don't want to publish anything
+if (!System.env.TEAMCITY_VERSION) {
+    project(':clean') {
+        evaluationDependsOn(':mcp')
+        apply plugin: 'net.minecraftforge.gradle.patcher'
+        tasks.withType(AbstractPublishToMaven.class).forEach{tsk -> tsk.enabled = false } // We don't want to publish anything
 
-    dependencies {
-        implementation 'net.minecraftforge:forgespi:' + SPI_VERSION
-    }
+        dependencies {
+            implementation 'net.minecraftforge:forgespi:' + SPI_VERSION
+        }
 
-    patcher {
-        parent = project(':mcp')
-        mcVersion = MC_VERSION
-        patchedSrc = file('src/main/java')
+        patcher {
+            parent = project(':mcp')
+            mcVersion = MC_VERSION
+            patchedSrc = file('src/main/java')
 
-        mappings channel: MAPPING_CHANNEL, version: MAPPING_VERSION
+            mappings channel: MAPPING_CHANNEL, version: MAPPING_VERSION
 
-        runs {
-            clean_client {
-                client true
-                taskName 'clean_client'
-                ideaModule "${rootProject.name}.${project.name}.main"
+            runs {
+                clean_client {
+                    client true
+                    taskName 'clean_client'
+                    ideaModule "${rootProject.name}.${project.name}.main"
 
-                main 'net.minecraft.client.main.Main'
-                workingDirectory project.file('run')
+                    main 'net.minecraft.client.main.Main'
+                    workingDirectory project.file('run')
 
-                args '--gameDir', '.'
-                args '--version', MC_VERSION
-                args '--assetsDir', downloadAssets.output
-                args '--assetIndex', '{asset_index}'
-                args '--accessToken', '0'
-            }
+                    args '--gameDir', '.'
+                    args '--version', MC_VERSION
+                    args '--assetsDir', downloadAssets.output
+                    args '--assetIndex', '{asset_index}'
+                    args '--accessToken', '0'
+                }
 
-            clean_server {
-                client false
-                taskName 'clean_server'
-                ideaModule "${rootProject.name}.${project.name}.main"
+                clean_server {
+                    client false
+                    taskName 'clean_server'
+                    ideaModule "${rootProject.name}.${project.name}.main"
 
-                main 'net.minecraft.server.Main'
-                workingDirectory project.file('run')
+                    main 'net.minecraft.server.Main'
+                    workingDirectory project.file('run')
+                }
             }
         }
     }
@@ -251,6 +273,7 @@ def sharedDeps = {
     moduleonly "org.ow2.asm:asm-util:${ASM_VERSION}"
     moduleonly "org.ow2.asm:asm-analysis:${ASM_VERSION}"
     moduleonly "cpw.mods:bootstraplauncher:${BOOTSTRAPLAUNCHER_VERSION}"
+    moduleonly "net.minecraftforge:JarJarFileSystems:${JARJAR_VERSION}"
 
     installer "cpw.mods:securejarhandler:${SECUREJARHANDLER_VERSION}"
     installer "org.ow2.asm:asm:${ASM_VERSION}"
@@ -259,21 +282,25 @@ def sharedDeps = {
     installer "org.ow2.asm:asm-util:${ASM_VERSION}"
     installer "org.ow2.asm:asm-analysis:${ASM_VERSION}"
     installer "net.minecraftforge:accesstransformers:${ACCESSTRANSFORMERS_VERSION}"
-    installer 'org.antlr:antlr4-runtime:4.9.1' //Dep of AccessTransformer
+    installer 'org.antlr:antlr4-runtime:4.9.1' // Dep of AccessTransformer
     installer "net.minecraftforge:eventbus:${EVENTBUS_VERSION}"
     installer "net.minecraftforge:forgespi:${SPI_VERSION}"
     installer "net.minecraftforge:coremods:${COREMODS_VERSION}"
     installer "cpw.mods:modlauncher:${MODLAUNCHER_VERSION}"
     installer 'net.minecraftforge:unsafe:0.2.+'
-    installer 'com.electronwill.night-config:core:3.6.4'
-    installer 'com.electronwill.night-config:toml:3.6.4'
-    installer 'org.apache.maven:maven-artifact:3.6.3'
+    installer "com.electronwill.night-config:core:${NIGHTCONFIG_VERSION}"
+    installer "com.electronwill.night-config:toml:${NIGHTCONFIG_VERSION}"
+    installer "org.apache.maven:maven-artifact:${APACHE_MAVEN_ARTIFACT_VERSION}"
     installer 'net.jodah:typetools:0.8.3'
-    installer 'net.minecrell:terminalconsoleappender:1.2.0'
-    installer 'org.jline:jline-reader:3.12.+'   //Dep of TerminaalConsoleeAppender
-    installer 'org.jline:jline-terminal:3.12.+' //Dep of TerminaalConsoleeAppender
+    installer "net.minecrell:terminalconsoleappender:${TERMINALCONSOLEAPPENDER_VERSION}"
+    installer "org.jline:jline-reader:${JLINE_VERSION}"   // Dep of TerminalConsoleAppender
+    installer "org.jline:jline-terminal:${JLINE_VERSION}" // Dep of TerminalConsoleAppender
     installer "org.spongepowered:mixin:${MIXIN_VERSION}"
-    installer 'org.openjdk.nashorn:nashorn-core:15.3'
+    installer 'org.openjdk.nashorn:nashorn-core:15.4'
+    installer "net.minecraftforge:JarJarSelector:${JARJAR_VERSION}"
+    installer "net.minecraftforge:JarJarMetadata:${JARJAR_VERSION}"
+    installer 'net.java.dev.jna:jna:5.12.1'
+    installer 'net.java.dev.jna:jna-platform:5.12.1'
 
     /*
     installer 'org.lwjgl:lwjgl:3.2.2'
@@ -324,7 +351,7 @@ def sharedFmlonlyForge = { Project prj ->
     }
 
     prj.task([type: DownloadMavenArtifact], 'downloadInstaller') {
-        artifact = "net.minecraftforge:installer:${INSTALLER_VERSION}:shrunk"
+        artifact = "net.minecraftforge:installer:${INSTALLER_VERSION}:fatjar"
         changing = true
     }
 
@@ -366,7 +393,8 @@ def sharedFmlonlyForge = { Project prj ->
                 environment 'MOD_CLASSES', '{source_roots}'
                 environment 'MCP_MAPPINGS', '{mcp_mappings}'
 
-                property 'nativesDirectory', '{natives}'
+                // Natives are loaded from the classpath now in all cases
+                // property 'nativesDirectory', '{natives}'
                 if (prj.name == 'forge') {
                     property 'forge.enableGameTest', 'true'
                 }
@@ -420,6 +448,8 @@ def sharedFmlonlyForge = { Project prj ->
         run.args '--fml.forgeGroup', prj.group
         run.args '--fml.mcpVersion', MCP_VERSION
 
+        run.jvmArgs '-Djava.net.preferIPv6Addresses=system'
+
         if (run.name.contains('client')) {
             run.client true
         } else {
@@ -429,7 +459,7 @@ def sharedFmlonlyForge = { Project prj ->
         // SecureJarHandler bootstrap values.
         run.property 'ignoreList', prj.configurations.moduleonly.files.collect {it.name.replaceAll(/([-_]([.\d]*\d+)|\.jar$)/, '') }.join(',') + ",client-extra,fmlcore,javafmllanguage,lowcodelanguage,mclanguage,${prj.name}-"
         // FIXME: Without this jna doesn't work at runtime. Someone figure out why please?
-        run.property 'mergeModules', 'jna-5.10.0.jar,jna-platform-5.10.0.jar,java-objc-bridge-1.0.0.jar'
+        run.property 'mergeModules', 'jna-5.12.1.jar,jna-platform-5.12.1.jar'
         if (userdevRuns.contains(run)) {
             run.property 'legacyClassPath.file', '{minecraft_classpath_file}'
             run.jvmArgs '-p', '{modules}'
@@ -440,6 +470,7 @@ def sharedFmlonlyForge = { Project prj ->
         run.jvmArgs '--add-modules', 'ALL-MODULE-PATH'
         // Additions to these JVM module args should be mirrored to server_files/args.txt and other similar blocks in the buildscript
         run.jvmArgs '--add-opens', 'java.base/java.util.jar=cpw.mods.securejarhandler'
+        run.jvmArgs '--add-opens', 'java.base/java.lang.invoke=cpw.mods.securejarhandler'
         run.jvmArgs '--add-exports', 'java.base/sun.security.util=cpw.mods.securejarhandler'
         run.jvmArgs '--add-exports', 'jdk.naming.dns/com.sun.jndi.dns=java.naming'
     }
@@ -448,7 +479,8 @@ def sharedFmlonlyForge = { Project prj ->
         run.workingDirectory prj.file('run')
 
         if (run.name.contains('client') || run.name.contains('data')) {
-            run.property 'nativesDirectory', prj.extractNatives.output.get().asFile
+            // Natives are loaded from the classpath now in all cases
+            // run.property 'nativesDirectory', prj.extractNatives.output.get().asFile
             run.args '--assetsDir', prj.downloadAssets.output
             run.args '--assetIndex', "{asset_index}"
         }
@@ -630,6 +662,7 @@ project(':fmlonly') {
                           '--add-modules', 'ALL-MODULE-PATH',
                           // Additions to these JVM module args should be mirrored to server_files/args.txt and other similar blocks in the buildscript
                           '--add-opens', 'java.base/java.util.jar=cpw.mods.securejarhandler',
+                          '--add-opens', 'java.base/java.lang.invoke=cpw.mods.securejarhandler',
                           '--add-exports', 'java.base/sun.security.util=cpw.mods.securejarhandler',
                           '--add-exports', 'jdk.naming.dns/com.sun.jndi.dns=java.naming'
                     ]
@@ -852,11 +885,15 @@ project(':fmlonly') {
 }
 
 project(':forge') {
-    evaluationDependsOn(':clean')
+    evaluationDependsOn(System.env.TEAMCITY_VERSION ? ':mcp' : ':clean')
     apply plugin: 'java-library'
     apply plugin: 'net.minecraftforge.gradle.patcher'
     apply plugin: 'org.cadixdev.licenser'
 
+    applyPatches { 
+        level 'WARNING'
+    }
+
     sourceSets {
         main {
             java {
@@ -926,13 +963,19 @@ project(':forge') {
 
     patcher {
         excs.from file("$rootDir/src/main/resources/forge.exc")
-        parent = project(':clean')
+        parent = project(System.env.TEAMCITY_VERSION ? ':mcp' : ':clean')
         patches = file("$rootDir/patches/minecraft")
         patchedSrc = file('src/main/java')
         srgPatches = true
         accessTransformers.from file("$rootDir/src/main/resources/META-INF/accesstransformer.cfg")
         sideAnnotationStrippers.from file("$rootDir/src/main/resources/forge.sas")
 
+        // the clean project provides these. if we're not using it, we need to provide them ourselves
+        if (System.env.TEAMCITY_VERSION) {
+            mappings channel: MAPPING_CHANNEL, version: MAPPING_VERSION
+            mcVersion = MC_VERSION
+        }
+
         runs {
             forge_client {
                 property 'eventbus.checkTypesOnDispatch', 'true'
@@ -1049,11 +1092,40 @@ project(':forge') {
                             '--mod', 'tag_based_tool_types',
                             '--mod', 'custom_transformtype_test',
                             '--mod', 'data_pack_registries_test',
+                            '--mod', 'biome_modifiers_test',
+                            '--mod', 'structure_modifiers_test',
+                            '--mod', 'custom_preset_editor_test',
                             '--output', rootProject.file('src/generated_test/resources/'),
                             '--existing', sourceSets.main.resources.srcDirs[0],
                             '--existing', sourceSets.test.resources.srcDirs[0]
                 }
             }
+
+            forge_mdk_data {
+                parent runs.forge_data
+                taskName 'forge_mdk_data'
+
+                environment 'MOD_CLASSES', 'dummy' // Needed to work around FG limitation, FG will replace this!
+
+                ideaModule "${rootProject.name}.${project.name}.test"
+
+                mods {
+                    tests { sources sourceSets.test }
+                }
+
+                afterEvaluate {
+                    // Clear forge's main datagen args
+                    args.removeAll {
+                        forgeDataArgs.contains(it instanceof File ? (it as File).absolutePath : it.toString())
+                    }
+
+                    args '--flat', '--all', '--validate',
+                            '--mod', 'mdk_datagen',
+                            '--output', rootProject.file('src/generated_mdk/resources/'),
+                            '--existing', sourceSets.main.resources.srcDirs[0],
+                            '--existing', sourceSets.test.resources.srcDirs[0]
+                }
+            }
         }
     }
 
@@ -1108,9 +1180,12 @@ project(':forge') {
         ]
     }
 
-    task crowdin(type: Crowdin) {
-        key = project.hasProperty('crowdinKey') ? project.crowdinKey : null
-        //TODO: Merge our english.json?
+    tasks.register('downloadCrowdin', Download) {
+        src 'https://files.minecraftforge.net/crowdin.zip'
+        dest file('build/crowdin.zip')
+        useETag 'all'
+        onlyIfModified true
+        quiet true
     }
 
     sharedFmlonlyForge.call(project)
@@ -1146,86 +1221,117 @@ project(':forge') {
         }
     }
 
-    task checkATs(type: CheckATs, dependsOn: [extractInheritance, createSrg2Mcp]) {
-        inheritance = extractInheritance.output
+    task findFinalizeSpawnTargets(type: BytecodePredicateFinder, dependsOn: ['createJoinedSRG']) {
+        jar = createJoinedSRG.output
+        output = rootProject.file('src/main/resources/coremods/finalize_spawn_targets.json')
+        predicate = {
+            parent, node, insn ->
+                'net/minecraft/world/level/BaseSpawner' != parent.name // Ignore this class as we special case it.
+                && insn.getOpcode() == Opcodes.INVOKEVIRTUAL
+                && insn.name.equals('m_6518_')
+                && insn.desc.equals('(Lnet/minecraft/world/level/ServerLevelAccessor;Lnet/minecraft/world/DifficultyInstance;Lnet/minecraft/world/entity/MobSpawnType;Lnet/minecraft/world/entity/SpawnGroupData;Lnet/minecraft/nbt/CompoundTag;)Lnet/minecraft/world/entity/SpawnGroupData;')
+        }
+    }
+
+    tasks.register('validateDeprecations', ValidateDeprecations) {
+        input = tasks.jar.archiveFile
+        mcVersion = MC_VERSION
+    }
+
+    tasks.jar.finalizedBy 'validateDeprecations'
+
+    tasks.register('checkAll') {
+        dependsOn 'checkLicenses'
+        group = 'checks'
+    }
+    tasks.register('checkAllAndFix') {
+        dependsOn 'findFinalizeSpawnTargets', 'findFieldInstanceChecks', 'checkLicenses'
+        group = 'checks'
+    }
+
+    CheckTask.registerTask(tasks, 'ATs', CheckATs) {
+        dependsOn extractInheritance, createSrg2Mcp
         ats.from patcher.accessTransformers
+        inheritance = extractInheritance.output
         mappings = createSrg2Mcp.output
     }
 
-    task checkSAS(type: CheckSAS, dependsOn: extractInheritance) {
-        inheritance = extractInheritance.output
+    CheckTask.registerTask(tasks, 'SAS', CheckSAS) {
+        dependsOn extractInheritance
         sass.from patcher.sideAnnotationStrippers
+        inheritance = extractInheritance.output
     }
 
-    task checkExcs(type: CheckExcs, dependsOn: jar) {
+    CheckTask.registerTask(tasks, 'Excs', CheckExcs) {
+        dependsOn jar
         binary = jar.archiveFile.get().asFile
         excs.from patcher.excs
     }
 
-    task checkAll(dependsOn: [checkATs, checkSAS, checkExcs, findFieldInstanceChecks]){}
-
-    task checkPatchesAndFix(type: CheckPatches, dependsOn: genPatches) {
+    CheckTask.registerTask(tasks, 'Patches', CheckPatches) {
+        dependsOn genPatches
         patchDir = file("$rootDir/patches")
-        autoFix = true
-    }
-
-    task checkPatches(type: CheckPatches, dependsOn: genPatches) {
-        patchDir = file("$rootDir/patches")
-        autoFix = false
+        patchesWithS2SArtifact = [
+                'minecraft/net/minecraft/client/renderer/ViewArea.java.patch',
+                'minecraft/net/minecraft/data/models/blockstates/Variant.java.patch',
+        ]
     }
 
     genPatches {
-        finalizedBy checkPatches
+        finalizedBy checkAndFixPatches
         autoHeader true
         lineEnding = '\n'
     }
 
-    def baseForgeVersion = LAST_RB == null ? null : "${MC_VERSION}-${LAST_RB}"
-
-    task downloadBaseCompatibilityBinPatches(type: DownloadBaseCompatibilityBinPatches) {
-        inputVersion = baseForgeVersion
+    def baseForgeVersionProperty = project.objects.property(String)
+    baseForgeVersionProperty.set(project.provider { TeamcityRequests.attemptFindBase(rootDir) ?: getLatestForgeVersion(MC_VERSION) })
+    baseForgeVersionProperty.finalizeValueOnRead()
+    def jarCompatibilityTaskSetup = { task ->
+        task.group = 'jar compatibility'
+        task.onlyIf {
+            baseForgeVersionProperty.getOrNull() != null
+        }
     }
 
-    task applyBaseCompatibilityJarBinPatches(type: ApplyBinPatches) {
-        group = 'jar compatibility'
-        onlyIf {
-            baseForgeVersion != null
-        }
-        inputs.property 'baseForgeVersion', baseForgeVersion
+    tasks.register('setupCheckJarCompatibility', SetupCheckJarCompatibility) {
+        inputVersion = baseForgeVersionProperty
+    }
 
-        clean = createJoinedSRG.output
-        patch = downloadBaseCompatibilityBinPatches.output
+    tasks.register('applyBaseCompatibilityJarBinPatches', ApplyBinPatches) {
+        jarCompatibilityTaskSetup(it)
+
+        clean = project.tasks.createJoinedSRG.output
+        patch = project.tasks.named('setupCheckJarCompatibility').flatMap { it.baseBinPatchesOutput }
         output = project.layout.buildDirectory.dir(name).map { it.file('output.jar') }
     }
 
-    task checkJarCompatibility(type: CheckJarCompatibility) {
-        group = 'jar compatibility'
-        onlyIf {
-            baseForgeVersion != null
-        }
-        inputs.property 'baseForgeVersion', baseForgeVersion
+    tasks.register('mergeBaseForgeJar', MergeJars) {
+        jarCompatibilityTaskSetup(it)
 
-        if (baseForgeVersion != null) {
-            def baseForgeUniversal = project.configurations.detachedConfiguration(project.dependencies.create("net.minecraftforge:forge:${baseForgeVersion}:universal"))
-            def fmlLibs = project.configurations.detachedConfiguration(PACKED_DEPS.collect {
-                def artifactId = it.split(':')[1]
-                return project.dependencies.create("net.minecraftforge:${artifactId}:${baseForgeVersion}")
-            }.toArray(Dependency[]::new))
+        inputJars.from(project.tasks.named('applyBaseCompatibilityJarBinPatches').flatMap { it.output })
+        inputJars.from(baseForgeVersionProperty.map { inputVersion ->
+            def output = project.layout.buildDirectory.dir(name).map { it.file("forge-${inputVersion}-universal.jar") }.get().asFile
+            project.rootProject.extensions.download.run {
+                src "https://maven.minecraftforge.net/net/minecraftforge/forge/${inputVersion}/forge-${inputVersion}-universal.jar"
+                dest output
+            }
+            return output
+        })
+    }
 
-            baseJar = project.tasks.applyBaseCompatibilityJarBinPatches.output
-            baseLibraries.from(project.file(project.provider {
-                baseForgeUniversal.resolve().iterator().next()
-            }))
-            baseLibraries.from(project.tasks.createJoinedSRG.output)
-            baseLibraries.from(fmlLibs)
+    tasks.register('checkJarCompatibility', CheckJarCompatibility) {
+        jarCompatibilityTaskSetup(it)
+        dependsOn 'setupCheckJarCompatibility'
 
-            inputJar = project.tasks.reobfJar.output
-            concreteLibraries.from(PACKED_DEPS.collect { rootProject.tasks.getByPath(it).archiveFile })
+        baseJar = project.tasks.named('mergeBaseForgeJar').flatMap { it.output }
+        baseLibraries.from(project.tasks.named('createJoinedSRG').flatMap { it.output })
 
-            commonLibraries.from(project.configurations.minecraftImplementation)
-            commonLibraries.from(project.configurations.installer)
-            commonLibraries.from(project.configurations.moduleonly)
-        }
+        inputJar = project.tasks.named('reobfJar').flatMap { it.output }
+        concreteLibraries.from(project.PACKED_DEPS.collect { project.rootProject.tasks.getByPath(it).archiveFile })
+
+        commonLibraries.from(project.configurations.minecraftImplementation)
+        commonLibraries.from(project.configurations.installer)
+        commonLibraries.from(project.configurations.moduleonly)
     }
 
     task launcherJson(type: LauncherJson) {
@@ -1247,13 +1353,15 @@ project(':forge') {
                            '--fml.mcVersion', MC_VERSION,
                            '--fml.forgeGroup', project.group,
                            '--fml.mcpVersion', MCP_VERSION],
-                    jvm: ["-DignoreList=${forge_client.properties.ignoreList},\${version_name}.jar",
+                    jvm: ['-Djava.net.preferIPv6Addresses=system',
+                          "-DignoreList=${forge_client.properties.ignoreList},\${version_name}.jar",
                           "-DmergeModules=${forge_client.properties.mergeModules}",
                           '-DlibraryDirectory=${library_directory}',
                           '-p', Util.getArtifacts(project, configurations.moduleonly, false).values().collect{'${library_directory}/' + it.downloads.artifact.path}.join('${classpath_separator}'),
                           '--add-modules', 'ALL-MODULE-PATH',
                           // Additions to these JVM module args should be mirrored to server_files/args.txt and other similar blocks in the buildscript
                           '--add-opens', 'java.base/java.util.jar=cpw.mods.securejarhandler',
+                          '--add-opens', 'java.base/java.lang.invoke=cpw.mods.securejarhandler',
                           '--add-exports', 'java.base/sun.security.util=cpw.mods.securejarhandler',
                           '--add-exports', 'jdk.naming.dns/com.sun.jndi.dns=java.naming'
                     ]
@@ -1483,9 +1591,12 @@ project(':forge') {
         from extraTxts
 
         // add crowdin locales
-        from { crowdin.output.present && crowdin.output.get().asFile.exists() ? zipTree(crowdin.output) : null}
-        dependsOn crowdin
-        duplicatesStrategy = 'exclude'
+        from zipTree(downloadCrowdin.dest).matching {
+            include 'assets/forge/lang/*.json'
+        }
+
+        dependsOn downloadCrowdin
+        duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 
         doFirst {
             MANIFESTS.each{ pkg, values ->
@@ -1530,18 +1641,22 @@ project(':forge') {
                     exclude it
             }
             filter(ReplaceTokens, tokens: [
-                FORGE_VERSION: project.version,
+                FORGE_VERSION: FORGE_VERSION,
                 FORGE_GROUP: project.group,
                 FORGE_NAME: project.name,
                 MC_VERSION: MC_VERSION,
                 MAPPING_CHANNEL: MAPPING_CHANNEL,
                 MAPPING_VERSION: MAPPING_VERSION,
                 FORGE_SPEC_VERSION: SPEC_VERSION.split("\\.")[0],
-                MC_NEXT_VERSION: "1."+((MC_VERSION.split("[\\.-]")[1] as int)+1)
+                MC_NEXT_VERSION: MC_NEXT_VERSION
             ])
             rename 'gitignore\\.txt', '.gitignore'
             rename 'gitattributes\\.txt', '.gitattributes'
         }
+        from(rootProject.file('src/generated_mdk/resources/')) {
+            into('src/main/resources/')
+            exclude '**/.cache/'
+        }
     }
 
     license {
@@ -1578,6 +1693,83 @@ project(':forge') {
         sourceSets.test.java.srcDirs.each { extractMappedNew.addTarget it }
     }
 
+    tasks.named('javadoc', Javadoc).configure {
+        description 'Generates the combined javadocs for the FML projects and the main Forge project'
+        var includedProjects = [ ':fmlcore', ':fmlloader', ':javafmllanguage', ':mclanguage' ]
+        source includedProjects.collect { project(it).sourceSets.main.allJava }
+        classpath = classpath + files(includedProjects.collect { project(it).sourceSets.main.compileClasspath })
+
+        var docsDir = rootProject.file('src/docs/')
+        inputs.dir(docsDir)
+            .withPropertyName('docs resources directory')
+            .withPathSensitivity(PathSensitivity.RELATIVE)
+            .optional()
+
+        failOnError = false
+
+        // Exclude the Minecraft classes if not enabled
+        if (!project.hasProperty('generateAllDocumentation')) {
+            exclude 'net/minecraft/**'
+            exclude 'com/mojang/**'
+        }
+        exclude 'mcp/**'
+
+        options.addStringOption('Xdoclint:all,-missing', '-public')
+        options {
+            stylesheetFile = new File(docsDir, 'stylesheet.css')
+
+            tags = [
+                'apiNote:a:<em>API Note:</em>',
+                'implSpec:a:<em>Implementation Requirements:</em>',
+                'implNote:a:<em>Implementation Note:</em>'
+            ]
+
+            groups = [
+                'Forge Mod Loader': [
+                    'net.minecraftforge.fml.common.asm*',
+                    'net.minecraftforge.fml.loading*',
+                    'net.minecraftforge.fml.server*'
+                ],
+                'FML Core':  [
+                    'net.minecraftforge.fml',
+                    'net.minecraftforge.fml.config*',
+                    'net.minecraftforge.fml.event*',
+                    'net.minecraftforge.fml.util*'
+                ],
+                'FML Common': [
+                    'net.minecraftforge.fml.core',
+                    'net.minecraftforge.fml.event.config',
+                    'net.minecraftforge.fml.event.lifecycle'
+                ],
+                'FML Java/MC Language Providers': [
+                    'net.minecraftforge.fml.common',
+                    'net.minecraftforge.fml.javafmlmod',
+                    'net.minecraftforge.fml.mclanguageprovider'
+                ],
+                'Minecraft Forge API': [
+                    'net.minecraftforge*'
+                ]
+            ]
+
+            author = false
+            noSince = true
+            noHelp = true
+
+            bottom = "Minecraft Forge is an open source modding API for Minecraft: Java Edition, licensed under the Lesser GNU General Public License, version 2.1."
+            windowTitle = "Minecraft Forge API ${VERSION}"
+            docTitle = "Minecraft Forge API - ${FORGE_VERSION} for Minecraft ${MC_VERSION}"
+            header = "<div style=\"margin-top: 9px;padding: 5px 6px;\"><strong>${FORGE_VERSION} for Minecraft ${MC_VERSION}</strong></div>"
+        }
+
+        doLast {
+            project.copy {
+                from docsDir
+                exclude '/stylesheet.css'
+                into destinationDir
+            }
+        }
+    }
+
     publishing {
         publications {
             mavenJava(MavenPublication) {
@@ -1600,7 +1792,8 @@ project(':forge') {
 
 //evaluationDependsOnChildren()
 task setup() {  //These must be strings so that we can do lazy resolution. Else we need evaluationDependsOnChildren above
-    dependsOn ':clean:extractMapped'
+    if (!System.env.TEAMCITY_VERSION)
+        dependsOn ':clean:extractMapped'
     if (symlinkValid)
         dependsOn ':fmlonly:extractMapped'
     dependsOn ':forge:extractMapped'
@@ -1616,4 +1809,12 @@ if (System.env.TEAMCITY_VERSION) {
             println "##teamcity[setParameter name='env.PUBLISHED_JAVA_FML_ARTIFACT_VERSION' value='${project(':fmlonly').version}']"
         }
     }
-}
+}
+
+idea {
+    module {
+        // IntelliJ IDEA does not do this by itself anymore...
+        downloadJavadoc = true
+        downloadSources = true
+    }
+}

buildSrc/build.gradle

@@ -2,8 +2,12 @@ repositories {
     maven { url = 'https://maven.minecraftforge.net/' }
 	mavenCentral()
 }
+
 dependencies {
-	implementation 'org.ow2.asm:asm:9.1'
-	implementation 'org.ow2.asm:asm-tree:9.1'
-    implementation 'net.minecraftforge:srgutils:0.4.+'
+    implementation 'org.ow2.asm:asm:9.5'
+    implementation 'org.ow2.asm:asm-tree:9.5'
+    implementation 'net.minecraftforge:srgutils:0.5.+'
+    implementation 'commons-io:commons-io:2.12.0'
+    implementation 'com.google.code.gson:gson:2.10.1'
+    implementation 'org.eclipse.jgit:org.eclipse.jgit:6.5.0.202303070854-r'
 }

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/BytecodeFinder.groovy

@@ -4,20 +4,17 @@ import groovy.json.JsonBuilder
 import org.gradle.api.DefaultTask
 import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.tasks.InputFile
-import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.TaskAction
-import org.objectweb.asm.ClassReader
-import org.objectweb.asm.Opcodes
 import org.objectweb.asm.tree.ClassNode
 import org.objectweb.asm.tree.FieldNode
 import org.objectweb.asm.tree.MethodNode
 
-import java.util.zip.ZipEntry
-import java.util.zip.ZipInputStream
-
 abstract class BytecodeFinder extends DefaultTask {
     @InputFile abstract RegularFileProperty getJar()
-    @OutputFile abstract RegularFileProperty getOutput()
+    // It should be fine to mark the output as internal as we want to control when we run it anyways.
+    // This also shuts Gradle 8 up about implicit task dependencies.
+    @Internal abstract RegularFileProperty getOutput()
 
     BytecodeFinder() {
         output.convention(project.layout.buildDirectory.dir(name).map { it.file("output.json") })
@@ -33,18 +30,7 @@ abstract class BytecodeFinder extends DefaultTask {
 
         pre()
 
-        jar.get().asFile.withInputStream { i ->
-            new ZipInputStream(i).withCloseable { zin ->
-                ZipEntry zein
-                while ((zein = zin.nextEntry) != null) {
-                    if (zein.name.endsWith('.class')) {
-                        def node = new ClassNode(Opcodes.ASM9)
-                        new ClassReader(zin).accept(node, 0)
-                        process(node)
-                    }
-                }
-            }
-        }
+        Util.processClassNodes(jar.get().asFile, this::process)
 
         post()
         outputFile.text = new JsonBuilder(getData()).toPrettyString()

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/BytecodePredicateFinder.groovy

@@ -0,0 +1,32 @@
+package net.minecraftforge.forge.tasks
+
+import groovy.transform.CompileStatic
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Internal
+import org.objectweb.asm.tree.ClassNode
+import org.objectweb.asm.tree.MethodNode
+
+@CompileStatic
+abstract class BytecodePredicateFinder extends BytecodeFinder {
+
+    @Internal
+    abstract Property<Closure<Boolean>> getPredicate()
+
+    private final Set<String> matches = new HashSet()
+
+    @Override
+    protected process(ClassNode parent, MethodNode node) {
+        for (final current : node.instructions) {
+            if (predicate.get().call(parent, node, current)) {
+                matches.add(parent.name)
+                return
+            }
+        }
+    }
+
+    @Internal
+    @Override
+    protected Object getData() {
+        return matches.stream().sorted().toList() ?: {throw new RuntimeException('Failed to find any targets, please ensure that method names and descriptors are correct.')}()
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/CheckATs.groovy

@@ -1,267 +0,0 @@
-package net.minecraftforge.forge.tasks
-
-import net.minecraftforge.srgutils.IMappingFile
-import org.gradle.api.file.ConfigurableFileCollection
-import org.gradle.api.file.RegularFileProperty
-
-import org.gradle.api.DefaultTask
-import org.gradle.api.tasks.InputFile
-import org.gradle.api.tasks.InputFiles
-import org.gradle.api.tasks.Optional
-import org.gradle.api.tasks.TaskAction
-import org.objectweb.asm.Opcodes
-
-abstract class CheckATs extends DefaultTask {
-	@InputFile abstract RegularFileProperty getInheritance()
-	@InputFiles abstract ConfigurableFileCollection getAts()
-    @InputFile @Optional abstract RegularFileProperty getMappings()
-	
-    @TaskAction
-    protected void exec() {
-        def mappings = mappings.map { IMappingFile.load(it.asFile) }.getOrNull()
-		Util.init()
-		def parse = { line ->
-			def idx = line.indexOf('#')
-			def comment = idx == -1 ? null : line.substring(idx)
-			if (idx != -1) line = line.substring(0, idx - 1)
-			def (modifier, cls, desc) = (line.trim() + '     ').split(' ', -1)
-			def key = cls + (desc.isEmpty() ? '' : ' ' + desc)
-			return [modifier, cls, desc, comment, key]
-		}
-		def accessLevel = { access ->
-			if ((access & Opcodes.ACC_PUBLIC)    != 0) return 3
-			if ((access & Opcodes.ACC_PROTECTED) != 0) return 2
-			if ((access & Opcodes.ACC_PRIVATE)   != 0) return 0
-			return 1
-		}
-		def accessStr = { access ->
-			if (access.endsWith('-f') || access.endsWith('+f'))
-				return 4
-			switch (access.toLowerCase()) {
-				case 'public':    return 3
-				case 'protected': return 2
-				case 'default':   return 1
-				case 'private':   return 0
-				default:          return -1
-			}
-		}
-		def json = inheritance.get().asFile.json()
-		
-		ats.each { f -> 
-			TreeMap lines = [:]
-			def group = null
-			for (def line : f.readLines()) {
-				if (line.isEmpty()) continue
-				if (line.startsWith('#group ')) {
-					def (modifier, cls, desc, comment, key) = parse.call(line.substring(7))
-					
-					if (desc != '*' && desc != '*()' && desc != '<init>')
-						throw new IllegalStateException('Invalid group: ' + line)
-					
-					group = [modifier: modifier, cls: cls, desc: desc, comment: comment, 
-						existing: [] as Set,
-						children: [] as TreeSet,
-						group: true
-					]
-					if (lines.containsKey(key))
-						throw new IllegalStateException('Duplicate group: ' + line)
-					
-					lines[key] = group
-				} else if (group != null) {
-					if (line.startsWith('#endgroup')) {
-						group = null
-					} else {
-						def (modifier, cls, desc, comment, key) = parse.call(line)
-						group['existing'].add(key)
-					}
-				} else if (line.startsWith('#endgroup')) {
-					throw new IllegalStateException('Invalid group ending: ' + line)
-				} else if (line.startsWith('#')) {
-					//Nom
-				} else {
-					def (modifier, cls, desc, comment, key) = parse.call(line)
-					if (lines.containsKey(key)) {
-						println('Duplicate: ' + line)
-						continue
-					}
-					lines[key] = [modifier: modifier, cls: cls, desc: desc, comment: comment, group: false]
-				}
-			}
-			
-			// Process Groups, this will remove any entries outside the group that is covered by the group
-			for (def key : new ArrayList<>(lines.keySet())) {
-				def entry = lines.get(key)
-				if (entry != null && entry['group']) {
-					def cls = entry['cls']
-					def jcls = json.get(cls.replaceAll('\\.', '/'))
-					if (jcls == null) {
-						lines.remove(key)
-						println('Invalid Group: ' + key)
-					} else if ('*' == entry['desc']) {
-						if (!jcls.containsKey('fields')) {
-							lines.remove(key)
-							println('Invalid Group, Class has no fields: ' + key)
-						} else {
-							jcls['fields'].each { field, value ->
-								def fkey = cls + ' ' + field
-								if (accessLevel.call(value['access']) < accessStr.call(entry['modifier'])) {
-									if (lines.containsKey(fkey)) {
-										lines.remove(fkey)
-									} else if (!entry['existing'].contains(fkey)) {
-										println('Added: ' + fkey)
-									}
-									entry['children'].add(fkey)
-								} else if (lines.containsKey(fkey)) {
-									lines.remove(fkey)
-									println('Removed: ' + fkey)
-								}
-							}
-							entry['existing'].stream().findAll{ !entry['children'].contains(it) }.each{ println('Removed: ' + it) }
-						}
-					} else if ('*()' == entry['desc']) {
-						if (!jcls.containsKey('methods')) {
-							lines.remove(key)
-							println('Invalid Group, Class has no methods: ' + key)
-						} else {
-							jcls['methods'].each{ mtd, value ->
-								if (mtd.startsWith('<clinit>') || mtd.startsWith('lambda$'))
-									return
-								key = cls + ' ' + mtd.replace(' ', '')
-								if (accessLevel.call(value['access']) < accessStr.call(entry['modifier'])) {
-									if (lines.containsKey(key)) {
-										lines.remove(key)
-									} else if (!entry['existing'].contains(key)) {
-										println('Added: ' + key)
-									}
-									entry['children'].add(key)
-								} else if (lines.containsKey(key)) {
-									lines.remove(key)
-									println('Removed: ' + key)
-								}
-							}
-							entry['existing'].stream().findAll{ !entry['children'].contains(it) }.each{ println('Removed: ' + it) }
-						}
-					} else if ('<init>' == entry['desc']) { //Make all public non-abstract subclasses
-						json.each{ tcls,value -> 
-							if (!value.containsKey('methods') || ((value['access'] & Opcodes.ACC_ABSTRACT) != 0))
-								return
-							def parents = [] as Set
-							def parent = tcls
-							while (parent != null && json.containsKey(parent)) {
-								parents.add(parent)
-								def p = json[parent]
-								parent = p == null ? null : p['superName']
-							}
-							if (parents.contains(cls.replaceAll('\\.', '/'))) {
-								value['methods'].each{ mtd, v -> 
-									if (mtd.startsWith('<init>')) {
-										def child = tcls.replaceAll('/', '\\.') + ' ' + mtd.replace(' ', '')
-										if (accessLevel.call(v['access']) < 3) {
-											if (lines.containsKey(child)) {
-												lines.remove(child)
-											} else if (!entry['existing'].contains(child)) {
-												println('Added: ' + child)
-											}
-											entry['children'].add(child)
-										} else if (lines.containsKey(child)) {
-											lines.remove(child)
-											println('Removed: ' + child)
-										}
-									}
-								}
-							}
-						}
-						entry['existing'].stream().findAll{ !entry['children'].contains(it) }.each{ println('Removed: ' + it) }
-					}
-				}
-			}
-			
-			// Process normal lines, remove invalid and remove narrowing
-			for (def key : new ArrayList<>(lines.keySet())) {
-				def entry = lines.get(key)
-				if (entry != null && !entry['group']) {
-					def cls = entry['cls']
-					def jcls = json.get(cls.replaceAll('\\.', '/'))
-					if (jcls == null) {
-						lines.remove(key)
-						println('Invalid: ' + key)
-					} else if (entry['desc'] == '') {
-						if (accessLevel.call(jcls['access']) > accessStr.call(entry['modifier']) && (entry.comment == null || !entry.comment.startsWith('#force '))) {
-							lines.remove(key)
-							println('Invalid Narrowing: ' + key)
-						}
-					} else if (!entry['desc'].contains('(')) {
-						if (!jcls.containsKey('fields') || !jcls['fields'].containsKey(entry['desc'])) {
-							lines.remove(key)
-							println('Invalid: ' + key)
-						} else {
-							def value = jcls['fields'][entry['desc']]
-							if (accessLevel.call(value['access']) > accessStr.call(entry['modifier']) && (entry.comment == null || !entry.comment.startsWith('#force '))) {
-								lines.remove(key)
-								println('Invalid Narrowing: ' + key)
-								println(entry.comment)
-							}
-						}
-					} else {
-						def jdesc = entry['desc'].replace('(', ' (')
-						if (!jcls.containsKey('methods') || !jcls['methods'].containsKey(jdesc)) {
-							lines.remove(key)
-							println('Invalid: ' + key)
-						} else {
-							def value = jcls['methods'][jdesc]
-							if (accessLevel.call(value['access']) > accessStr.call(entry['modifier']) && (entry.comment == null || !entry.comment.startsWith('#force '))) {
-								lines.remove(key)
-								println('Invalid Narrowing: ' + key)
-							}
-						}
-					}
-				}
-			}
-
-			
-			def data = []
-            def remapComment = { entry ->
-                if (!mappings || !entry || !entry.desc) return null
-                def comment = entry.comment?.substring(1)?.trim()
-                def jsonCls = json.get(entry.cls.replaceAll('\\.', '/'))
-                def mappingsClass = mappings?.getClass(jsonCls.name)
-                if (!mappingsClass) return entry.comment
-                def idx = entry.desc.indexOf('(')
-                def mappedName = idx == -1
-                        ? mappingsClass.remapField(entry.desc)
-                        : mappingsClass.remapMethod(entry.desc.substring(0, idx), entry.desc.substring(idx))
-                if (!mappedName) return entry.comment
-                if (mappedName == '<init>')
-                    mappedName = 'constructor'
-
-                if (comment?.startsWith(mappedName))
-                    return '# ' + comment
-                if (comment && comment.indexOf(' ') != -1) {
-                    def split = comment.split(" - ").toList()
-                    if (split[0].indexOf(' ') != -1)
-                        // The first string is more than one word, so append before it
-                        return "# ${mappedName} - ${comment}"
-                    split.remove(0)
-                    return "# ${mappedName} - ${String.join(' - ', split)}"
-                }
-                return '# ' + mappedName
-            }
-			lines.each { key,value -> 
-				if (!value.group) {
-                    def comment = remapComment.call(value)
-					data.add(value.modifier + ' ' + key + (comment ? ' ' + comment : ''))
-				} else {
-					data.add('#group ' + value.modifier + ' ' + key + (value.comment == null ? '' : ' ' + value.comment))
-					value.children.each {
-                        def line = value.modifier + ' ' + it
-                        def (modifier, cls, desc, comment) = parse.call(line)
-                        comment = remapComment.call([modifier: modifier, cls: cls, desc: desc, comment: comment])
-                        data.add(line + (comment ? ' ' + comment : ''))
-                    }
-					data.add('#endgroup')
-				}
-			}
-			f.text = data.join('\n')
-		}
-	}
-}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/CheckExcs.groovy

@@ -1,94 +0,0 @@
-package net.minecraftforge.forge.tasks
-
-import org.gradle.api.file.ConfigurableFileCollection
-import org.gradle.api.file.RegularFileProperty
-
-import org.gradle.api.DefaultTask
-import org.gradle.api.tasks.InputFile
-import org.gradle.api.tasks.InputFiles
-import org.gradle.api.tasks.TaskAction
-
-import org.objectweb.asm.ClassReader
-import org.objectweb.asm.ClassVisitor
-import org.objectweb.asm.MethodVisitor
-import org.objectweb.asm.Opcodes
-import org.objectweb.asm.Type
-
-import java.util.zip.ZipEntry
-import java.util.zip.ZipInputStream
-
-abstract class CheckExcs extends DefaultTask {
-	@InputFile abstract RegularFileProperty getBinary()
-	@InputFiles abstract ConfigurableFileCollection getExcs()
-	
-    @TaskAction
-    protected void exec() {
-		Util.init()
-		def known = []
-		binary.get().asFile.withInputStream { i ->
-			new ZipInputStream(i).withCloseable { zin ->
-				def visitor = new ClassVisitor(Opcodes.ASM9) {
-					private String cls
-					@Override
-					public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
-						this.cls = name
-					}
-					
-					@Override
-					public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
-						known.add(this.cls + '.' + name + descriptor)
-						super.visitMethod(access, name, descriptor, signature, exceptions)
-					}
-				}
-				ZipEntry zein
-				while ((zein = zin.nextEntry) != null) {
-					if (zein.name.endsWith('.class')) {
-						ClassReader reader = new ClassReader(zin)
-						reader.accept(visitor, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES)
-					}
-				}
-			}
-		}
-		
-		excs.each { f -> 
-			def lines = []
-			f.eachLine { line ->
-				def idx = line.indexOf('#')
-				if (idx == 0 || line.isEmpty()) {
-					return
-				}
-				
-				def comment = idx == -1 ? null : line.substring(idx)
-				if (idx != -1) line = line.substring(0, idx - 1)
-				
-				if (!line.contains('=')) {
-					println('Invalid: ' + line)
-					return
-				}
-				
-				def (key, value) = line.split('=', 2)
-				if (!known.contains(key)) {
-					println('Unknown: ' + line)
-					return
-				}
-				
-				def (cls, desc) = key.split('\\.', 2)
-				if (!desc.contains('(')) {
-					println('Invalid: ' + line)
-					return
-				}
-				def name = desc.split('\\(', 2)[0]
-				desc = '(' + desc.split('\\(', 2)[1]
-				
-				def (exceptions, args) = value.contains('|') ? value.split('|', 2) : [value, '']
-				
-				if (args.split(',').length != Type.getArgumentTypes(desc).length) {
-					println('Invalid: ' + line)
-					return
-				}
-				lines.add(line)
-			}
-			f.text = lines.sort().join('\n')
-		}
-	}
-}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/CheckPatches.groovy

@@ -1,219 +0,0 @@
-package net.minecraftforge.forge.tasks
-
-import org.gradle.api.DefaultTask
-import org.gradle.api.file.DirectoryProperty
-import org.gradle.api.tasks.Input
-import org.gradle.api.tasks.InputDirectory
-import org.gradle.api.tasks.TaskAction
-
-import java.nio.file.Files
-import java.nio.file.Paths
-import java.util.regex.Pattern
-
-abstract class CheckPatches extends DefaultTask {
-    @InputDirectory abstract DirectoryProperty getPatchDir()
-    @Input boolean autoFix = false
-
-    @TaskAction
-    protected void exec() {
-        def hasS2SArtifact = [
-                Paths.get("patches/minecraft/net/minecraft/client/renderer/ViewArea.java.patch"),
-                Paths.get("patches/minecraft/net/minecraft/data/models/blockstates/Variant.java.patch")
-        ]
-
-        def verified = true;
-        patchDir.get().asFileTree.each { patch ->
-            def patchPath = project.rootDir.toPath().relativize(patch.toPath())
-            verified &= verifyPatch(patch, autoFix, patchPath.toString(), hasS2SArtifact.contains(patchPath))
-        }
-
-        if (!verified)
-            throw new RuntimeException('One or more patches failed verification. Check the log for errors.')
-    }
-
-    def verifyPatch(patch, fix, patchPath, hasS2SArtifact) {
-        def hunk_start_pattern = Pattern.compile('^@@ -[0-9,]* \\+[0-9,_]* @@$')
-        def white_space_pattern = Pattern.compile('^[+\\-]\\s*$')
-        def import_pattern = Pattern.compile('^[+\\-]\\s*import.*')
-        def field_pattern = Pattern.compile('^[+\\-][\\s]*((public|protected|private)[\\s]*)?(static[\\s]*)?(final)?([^=;]*)(=.*)?;\\s*$')
-        def method_pattern = Pattern.compile('^[+\\-][\\s]*((public|protected|private)[\\s]*)?(static[\\s]*)?(final)?([^(]*)[(]([^)]*)?[)]\\s*[{]\\s*$')
-        def class_pattern = Pattern.compile('^[+\\-][\\s]*((public|protected|private)[\\s]*)?(static[\\s]*)?(final[\\s]*)?(class|interface)([^{]*)[{]\\s*$')
-
-        def accessMap = [("private"):0, (null):1, ("protected"):2, ("public"):3]
-
-        def hasProblem = false;
-        def lines = patch.readLines()
-
-        def hunksStart = 0
-        def onlyWhiteSpace = false
-
-        def didFix = false
-        def newLines = []
-        def whiteSpaceErrors = []
-
-        // First two lines are file name ++/-- and we do not care
-        newLines.add(lines[0] + '\n')
-        newLines.add(lines[1] + '\n')
-
-        int i = 2
-        for (; i < lines.size(); ++i) {
-            def line = lines[i]
-            newLines.add(line + '\n')
-
-            if (hunk_start_pattern.matcher(line).find()) {
-                if (onlyWhiteSpace) {
-                    if (fix || hasS2SArtifact) {
-                        logger.lifecycle("Removing white space hunk starting at line {}, file: {}", hunksStart + 1, patchPath)
-                        def toRemove = i - hunksStart;
-                        while (toRemove-- > 0)
-                            newLines.remove(newLines.size() - 1)
-                        didFix = true
-                    }
-                    else {
-                        logger.lifecycle("Patch contains only white space hunk starting at line {}, file: {}", hunksStart + 1, patchPath)
-                        hasProblem = true
-                    }
-                }
-                else {
-                    if (!whiteSpaceErrors.empty)
-                        hasProblem = true
-                    whiteSpaceErrors.each { error -> logger.lifecycle(error) }
-                    whiteSpaceErrors.clear()
-                }
-                hunksStart = i
-                onlyWhiteSpace = true
-                continue
-            }
-
-            if (line.startsWithAny('+','-')) {
-                def prefixChange = false
-                def prevLine = lines[i - 1]
-
-                if (line.charAt(0) == (char)'+' && prevLine.charAt(0) == (char)'-') {
-                    def prevTrim = prevLine.substring(1).replaceAll("\\s", "")
-                    def currTrim = line.substring(1).replaceAll("\\s", "")
-
-                    if (prevTrim.equals(currTrim)) {
-                        prefixChange = true
-                    }
-
-                    def pMatcher = field_pattern.matcher(prevLine)
-                    def cMatcher = field_pattern.matcher(line)
-
-                    if (pMatcher.find() && cMatcher.find() &&
-                            pMatcher.group(6) == cMatcher.group(6) && // = ...
-                            pMatcher.group(5) == cMatcher.group(5) && // field name
-                            pMatcher.group(3) == cMatcher.group(3) && // static
-                            (accessMap[pMatcher.group(2)] < accessMap[cMatcher.group(2)] || pMatcher.group(4) != cMatcher.group(4))) {
-                        logger.lifecycle("Patch contains access changes or final removal at line {}, file: {}", i + 1, patchPath)
-                        hasProblem = true
-                    }
-
-                    pMatcher = method_pattern.matcher(prevLine)
-                    cMatcher = method_pattern.matcher(line)
-
-                    if (pMatcher.find() && cMatcher.find() &&
-                            pMatcher.group(6) == cMatcher.group(6) && // params
-                            pMatcher.group(5) == cMatcher.group(5) && // <T> void name
-                            pMatcher.group(3) == cMatcher.group(3) && // static
-                            (accessMap[pMatcher.group(2)] < accessMap[cMatcher.group(2)] || pMatcher.group(4) != cMatcher.group(4))) {
-                        logger.lifecycle("Patch contains access changes or final removal at line {}, file: {}", i + 1, patchPath)
-                        hasProblem = true
-                    }
-
-                    pMatcher = class_pattern.matcher(prevLine)
-                    cMatcher = class_pattern.matcher(line)
-
-                    if (pMatcher.find() && cMatcher.find() &&
-                            pMatcher.group(6) == cMatcher.group(6) && // ClassName<> extends ...
-                            pMatcher.group(5) == cMatcher.group(5) && // class | interface
-                            pMatcher.group(3) == cMatcher.group(3) && // static
-                            (accessMap[pMatcher.group(2)] < accessMap[cMatcher.group(2)] || pMatcher.group(4) != cMatcher.group(4))) {
-                        logger.lifecycle("Patch contains access changes or final removal at line {}, file: {}", i + 1, patchPath)
-                        hasProblem = true
-                    }
-                }
-
-                if (line.charAt(0) == (char)'-' && i + 1 < lines.size()) {
-                    def nextLine = lines[i + 1]
-                    if (nextLine.charAt(0) == (char)'+') {
-                        def nextTrim = nextLine.substring(1).replaceAll("\\s", "")
-                        def currTrim = line.substring(1).replaceAll("\\s", "")
-
-                        if (nextTrim.equals(currTrim)) {
-                            prefixChange = true
-                        }
-                    }
-                }
-
-                def isWhiteSpaceChange = white_space_pattern.matcher(line).find()
-
-                if (!prefixChange && !isWhiteSpaceChange) {
-                    onlyWhiteSpace = hasS2SArtifact && import_pattern.matcher(line).find()
-                }
-                else if (isWhiteSpaceChange) {
-                    def prevLineChange = prevLine.startsWithAny('+','-')
-                    def nextLineChange = i + 1 < lines.size() && lines[i + 1].startsWithAny('+','-')
-
-                    if (!prevLineChange && !nextLineChange) {
-                        whiteSpaceErrors.add(String.format("Patch contains white space change in valid hunk at line %d (cannot auto fix), file: %s", i + 1, patchPath))
-                    }
-                }
-
-                if (line.contains("\t")) {
-                    if (!fix) {
-                        logger.lifecycle("Patch contains tabs on line {}, file: {}", i + 1, patchPath)
-                        hasProblem = true
-                    }
-                    else {
-                        logger.lifecycle("Fixing tabs on line {}, file: {}", i + 1, patchPath)
-                        line = line.replaceAll('\t', '    ')
-                        newLines.remove(newLines.size() - 1)
-                        newLines.add(line + '\n')
-                        didFix = true
-                    }
-                }
-
-                if (import_pattern.matcher(line).find() && !hasS2SArtifact) {
-                    logger.lifecycle("Patch contains import change on line {}, file: {}", i + 1, patchPath)
-                    hasProblem = true
-                }
-            }
-        }
-
-        if (onlyWhiteSpace) {
-            if (fix || hasS2SArtifact) {
-                logger.lifecycle("Removing white space hunk starting at line {}, file: {}", hunksStart + 1, patchPath)
-                def toRemove = i - hunksStart;
-                while (toRemove-- > 0)
-                    newLines.remove(newLines.size() - 1)
-                didFix = true
-            }
-            else {
-                logger.lifecycle("Patch contains only white space hunk starting at line {}, file: {}", hunksStart + 1, patchPath)
-                hasProblem = true
-            }
-        }
-        else {
-            if (!whiteSpaceErrors.empty)
-                hasProblem = true
-            whiteSpaceErrors.each { error -> logger.lifecycle(error) }
-        }
-
-        if (didFix) {
-            if (newLines.size() <= 2) {
-                logger.lifecycle("Patch is now empty removing, file: {}", patchPath)
-                Files.delete(patch.toPath())
-            }
-            else {
-                if (!hasS2SArtifact)
-                    logger.lifecycle("*** Updating patch file. Please run setup then genPatches again. ***")
-                patch.withWriter('UTF-8') { writer ->
-                    newLines.each { l -> writer.write(l) }
-                }
-            }
-        }
-
-        return !hasProblem
-    }
-}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/CheckSAS.groovy

@@ -1,107 +0,0 @@
-package net.minecraftforge.forge.tasks
-
-import org.gradle.api.file.ConfigurableFileCollection
-import org.gradle.api.file.RegularFileProperty
-
-import org.gradle.api.DefaultTask
-import org.gradle.api.tasks.InputFile
-import org.gradle.api.tasks.InputFiles
-import org.gradle.api.tasks.TaskAction
-
-abstract class CheckSAS extends DefaultTask {
-	@InputFile abstract RegularFileProperty getInheritance()
-	@InputFiles abstract ConfigurableFileCollection getSass()
-	
-    @TaskAction
-    protected void exec() {
-		Util.init()
-		def json = inheritance.get().asFile.json()
-		
-		sass.each { f -> 
-			def lines = []
-			f.eachLine { line ->
-				if (line[0] == '\t') return //Skip any tabbed lines, those are ones we add
-				def idx = line.indexOf('#')
-				if (idx == 0 || line.isEmpty()) {
-					lines.add(line)
-					return
-				}
-				def comment = idx == -1 ? null : line.substring(idx)
-				if (idx != -1) line = line.substring(0, idx - 1)
-				def (cls, name, desc) = (line.trim().replace('(', ' (') + '     ').split(' ', -1)
-				cls = cls.replaceAll('\\.', '/')
-
-				if (json[cls] == null) {
-					println('Invalid: ' + line)
-				} else if (name.isEmpty()) { //Class SAS
-                    def toAdd = []
-                    def clsSided = isSided(json[cls])
-                    def sided = clsSided
-                    
-                    /* TODO: MergeTool doesn't do fields
-                    if (json[cls]['fields'] != null) {
-						for (entry in json[cls]['fields']) {
-                            if (isSided(entry.value)) {
-                                sided = true
-                                toAdd.add('\t' + cls + ' ' + entry.key)
-                            }
-						}
-                    }
-                    */
-					if (json[cls]['methods'] != null) {
-                        for (entry in json[cls]['methods']) {
-                            if (isSided(entry.value)) {
-                                sided = true
-                                toAdd.add('\t' + cls + ' ' + entry.key.replaceAll(' ', ''))
-                                findChildMethods(json, cls, entry.key).each { lines.add('\t' + it) }
-                                findChildMethods(json, cls, entry.key).each { println(line + ' -- ' + it) }
-                            } else if (clsSided) {
-                                findChildMethods(json, cls, entry.key).each { lines.add('\t' + it) }
-                                findChildMethods(json, cls, entry.key).each { println(line + ' -- ' + it) }
-                            }
-						}
-                    }
-                    
-                    if (sided) {
-                        lines.add(cls + (comment == null ? '' : ' ' + comment))
-                        lines.addAll(toAdd.sort())
-                    } else
-                        println('Invalid: ' + line)
-                    
-                } else if (desc.isEmpty()) { // Fields
-                    /* TODO: MergeTool doesn't do fields
-                    if (json[cls]['fields'] != null && isSided(json[cls]['fields'][name]))
-                        lines.add(cls + ' ' + name + (comment == null ? '' : ' ' + comment))
-                    else
-                    */
-                        println('Invalid: ' + line)
-                } else { // Methods
-                    if (json[cls]['methods'] == null || !isSided(json[cls]['methods'][name + ' ' + desc]))
-                        println('Invalid: ' + line)
-                    else {
-                        lines.add(cls + ' ' + name + desc + (comment == null ? '' : ' ' + comment))
-                        findChildMethods(json, cls, name + ' ' + desc).each { println(line + ' -- ' + it) }
-                        findChildMethods(json, cls, name + ' ' + desc).each { lines.add('\t' + it) }
-                    }
-                }
-			}
-			f.text = lines.join('\n')
-		}
-	}
-
-    protected static isSided(json) {
-        if (json == null || json['annotations'] == null)
-            return false
-        for (ann in json['annotations']) {
-            if ('Lnet/minecraftforge/api/distmarker/OnlyIn;'.equals(ann.desc))
-                return true
-        }
-        return false
-    }
-    
-	protected static findChildMethods(json, cls, desc)
-	{
-		return json.values().findAll{ it.methods != null && it.methods[desc] != null && it.methods[desc].override == cls && isSided(it.methods[desc]) }
-				.collect { it.name + ' ' + desc.replace(' ', '') } as TreeSet
-	}
-}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/DownloadBaseCompatibilityBinPatches.groovy

@@ -1,39 +0,0 @@
-package net.minecraftforge.forge.tasks
-
-import org.gradle.api.DefaultTask
-import org.gradle.api.file.RegularFileProperty
-import org.gradle.api.provider.Property
-import org.gradle.api.tasks.Input
-import org.gradle.api.tasks.Optional
-import org.gradle.api.tasks.OutputFile
-import org.gradle.api.tasks.TaskAction
-
-import java.nio.file.Files
-
-abstract class DownloadBaseCompatibilityBinPatches extends DefaultTask {
-    DownloadBaseCompatibilityBinPatches() {
-        group = 'jar compatibility'
-        onlyIf {
-            inputVersion.getOrNull() != null
-        }
-
-        output.convention(project.layout.buildDirectory.dir(name).map { it.file('joined.lzma') })
-    }
-
-    @TaskAction
-    void run() {
-        def dep = project.dependencies.create("net.minecraftforge:forge:${inputVersion.get()}:userdev")
-        def baseForgeUserdev = project.configurations.detachedConfiguration(dep).resolve().iterator().next()
-
-        def joinedLzma = project.zipTree(baseForgeUserdev).matching { it.include('joined.lzma') }.singleFile
-
-        Files.copy(joinedLzma.toPath(), output.get().asFile.toPath())
-    }
-
-    @Input
-    @Optional
-    abstract Property<String> getInputVersion()
-
-    @OutputFile
-    abstract RegularFileProperty getOutput()
-}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/InheritanceData.groovy

@@ -0,0 +1,49 @@
+package net.minecraftforge.forge.tasks
+
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import groovy.transform.CompileStatic
+import groovy.transform.TupleConstructor
+
+@CompileStatic
+@TupleConstructor
+final class InheritanceData implements Annotatable {
+    String name
+    int access
+    String superName
+    List<String> interfaces = []
+    Map<String, Method> methods = [:]
+    Map<String, Field> fields = [:]
+    List<Annotation> annotations = []
+
+    @TupleConstructor
+    static final class Method implements Annotatable {
+        int access
+        String override
+        List<Annotation> annotations = []
+    }
+
+    @TupleConstructor
+    static final class Field implements Annotatable {
+        int access
+        String desc
+        List<Annotation> annotations = []
+    }
+
+    @TupleConstructor
+    static final class Annotation {
+        String desc
+    }
+
+    private static final Gson GSON = new Gson()
+    static Map<String, InheritanceData> parse(File file) {
+        try (final reader = file.newReader()) {
+            return GSON.fromJson(reader, new TypeToken<Map<String, InheritanceData>>() {})
+        }
+    }
+}
+
+@CompileStatic
+interface Annotatable {
+    List<InheritanceData.Annotation> getAnnotations()
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/InstallerJar.groovy

@@ -6,7 +6,7 @@ import org.gradle.api.provider.SetProperty
 
 abstract class InstallerJar extends Zip {
     @Input @Optional abstract SetProperty<String> getPackedDependencies()
-    
+
     InstallerJar() {
         archiveClassifier.set('installer')
         archiveExtension.set('jar') // Needs to be Zip task to not override Manifest, so set extension
@@ -15,7 +15,7 @@ abstract class InstallerJar extends Zip {
         def installerJson = project.tasks.installerJson
         def launcherJson = project.tasks.launcherJson
         def downloadInstaller = project.tasks.downloadInstaller
-        
+
         dependsOn(installerJson, launcherJson, downloadInstaller)
         from(installerJson, launcherJson)
 
@@ -24,13 +24,13 @@ abstract class InstallerJar extends Zip {
             from(project.zipTree(downloadInstaller.output)) {
                 duplicatesStrategy = 'exclude'
             }
-            
-            if (!System.env.MAVEN_USER) {
+
+            if (!System.env.TEAMCITY_VERSION) {
                 dependsOn(project.universalJar)
                 from(project.universalJar) {
                     into '/maven/' + project.group.replace('.', '/') + '/' + project.universalJar.archiveBaseName.get() + '/' + project.version + '/'
                 }
-    
+
                 packedDependencies.get().forEach {
                     def jarTask = project.rootProject.getTasks().findByPath(it)
                     dependsOn(jarTask)

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/MergeJars.groovy

@@ -0,0 +1,44 @@
+package net.minecraftforge.forge.tasks
+
+import org.apache.commons.io.IOUtils
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.InputFiles
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+
+import java.util.zip.ZipEntry
+import java.util.zip.ZipInputStream
+import java.util.zip.ZipOutputStream
+
+abstract class MergeJars extends DefaultTask {
+    MergeJars() {
+        output.convention(project.layout.buildDirectory.dir(name).map { it.file('output.jar') })
+    }
+
+    @TaskAction
+    void run() {
+        def jars = inputJars.files
+
+        try (ZipOutputStream zout = new ZipOutputStream(new FileOutputStream(output.get().asFile))) {
+            for (def jar : jars) {
+                try (ZipInputStream zin = new ZipInputStream(new FileInputStream(jar))) {
+                    def entry
+                    while ((entry = zin.getNextEntry()) != null) {
+                        ZipEntry _new = new ZipEntry(entry.getName())
+                        _new.setTime(0) //SHOULD be the same time as the main entry, but NOOOO _new.setTime(entry.getTime()) throws DateTimeException, so you get 0, screw you!
+                        zout.putNextEntry(_new)
+                        IOUtils.copy(zin, zout)
+                    }
+                }
+            }
+        }
+    }
+
+    @InputFiles
+    abstract ConfigurableFileCollection getInputJars()
+
+    @OutputFile
+    abstract RegularFileProperty getOutput()
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/SetupCheckJarCompatibility.groovy

@@ -0,0 +1,57 @@
+package net.minecraftforge.forge.tasks
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.artifacts.Dependency
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.Optional
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+
+import java.nio.file.Files
+import java.nio.file.StandardCopyOption
+
+abstract class SetupCheckJarCompatibility extends DefaultTask {
+    SetupCheckJarCompatibility() {
+        group = 'jar compatibility'
+        onlyIf {
+            inputVersion.getOrNull() != null
+        }
+        outputs.upToDateWhen { false } // Never up to date, because this setup task should always run
+
+        baseBinPatchesOutput.convention(project.layout.buildDirectory.dir(name).map { it.file('joined.lzma') })
+    }
+
+    @TaskAction
+    void run() {
+        def inputVersion = inputVersion.get()
+        def fmlLibs = project.configurations.detachedConfiguration(project.PACKED_DEPS.collect {
+            def artifactId = it.split(':')[1]
+            return project.dependencies.create("net.minecraftforge:${artifactId}:${inputVersion}")
+        }.toArray(Dependency[]::new))
+
+        project.tasks.named('checkJarCompatibility') {
+            baseLibraries.from(project.provider {
+                fmlLibs.resolvedConfiguration.lenientConfiguration.files
+            })
+        }
+
+        def baseForgeUserdev = project.layout.buildDirectory.dir(name).map { it.file("forge-${inputVersion}-userdev.jar") }.get().asFile
+        project.rootProject.extensions.download.run {
+            src "https://maven.minecraftforge.net/net/minecraftforge/forge/${inputVersion}/forge-${inputVersion}-userdev.jar"
+            dest baseForgeUserdev
+        }
+
+        def joinedLzma = project.zipTree(baseForgeUserdev).matching { it.include('joined.lzma') }.singleFile
+
+        Files.copy(joinedLzma.toPath(), baseBinPatchesOutput.get().asFile.toPath(), StandardCopyOption.REPLACE_EXISTING)
+    }
+
+    @Input
+    @Optional
+    abstract Property<String> getInputVersion()
+
+    @OutputFile
+    abstract RegularFileProperty getBaseBinPatchesOutput()
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/TeamcityRequests.groovy

@@ -0,0 +1,74 @@
+package net.minecraftforge.forge.tasks
+
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import groovy.transform.CompileStatic
+import org.eclipse.jgit.api.Git
+
+import javax.annotation.Nullable
+import java.util.stream.Collectors
+
+@CompileStatic
+class TeamcityRequests {
+    public static final Gson GSON = new Gson()
+
+    @Nullable
+    static <T> T jsonRequest(TypeToken<T> clazz, String url) throws Exception {
+        final HttpURLConnection conn = (HttpURLConnection) URI.create(url).toURL().openConnection()
+        conn.setRequestProperty('Accept', 'application/json')
+        conn.setReadTimeout(5 * 1000)
+        conn.setConnectTimeout(5 * 1000)
+        conn.connect()
+
+        if (conn.responseCode !== 200) {
+            return null
+        }
+
+        try (final InputStream is = conn.getInputStream()) {
+            GSON.fromJson(new InputStreamReader(is), clazz.getType())
+        }
+    }
+
+    @Nullable
+    static Map<String, Build> buildsByCommit() throws IOException {
+        final Map<String, Build> builds = [:]
+        jsonRequest(new TypeToken<Builds>() {}, 'https://teamcity.minecraftforge.net/guestAuth/app/rest/builds?fields=build:(revisions,number)&locator=buildType:(id:MinecraftForge_MinecraftForge_MinecraftForge_MinecraftForge__Build),defaultFilter:false,count:300,status:SUCCESS')
+                ?.build?.forEach {
+            it.revisions.revision.each { rev -> builds[rev.version] = it }
+        }
+        return builds
+    }
+
+    @Nullable
+    static String attemptFindBase(File gitPath) {
+        try (final git = Git.open(gitPath)) {
+            final Map<String, Build> buildByCommit = buildsByCommit()
+            for (final commit in git.log().setMaxCount(100).call()) {
+                // Find the first commit which was built on CI
+                final build = buildByCommit[commit.id.name]
+                if (build) {
+                    return build.number
+                }
+            }
+        } catch (Exception ignored) {}
+        return null
+    }
+
+    static final class Builds {
+        public List<Build> build
+    }
+
+    static final class Build {
+        public String number
+        public Revisions revisions
+    }
+
+    static final class Revisions {
+        public int count
+        public List<Revision> revision
+    }
+
+    static final class Revision {
+        public String version
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/Util.groovy

@@ -2,13 +2,20 @@ package net.minecraftforge.forge.tasks
 
 import groovy.json.JsonBuilder
 import groovy.json.JsonSlurper
+import org.objectweb.asm.ClassReader
+import org.objectweb.asm.Opcodes
+import org.objectweb.asm.tree.ClassNode
 
 import java.io.File
 import java.security.MessageDigest
 import java.text.SimpleDateFormat
 import java.util.Date
+import java.util.zip.ZipEntry
+import java.util.zip.ZipInputStream
 
 public class Util {
+    static final ASM_LEVEL = Opcodes.ASM9
+
 	static void init() {
 		File.metaClass.sha1 = { ->
 			MessageDigest md = MessageDigest.getInstance('SHA-1')
@@ -18,17 +25,17 @@ public class Util {
 			return md.digest().collect {String.format "%02x", it}.join()
 		}
         File.metaClass.getSha1 = { !delegate.exists() ? null : delegate.sha1() }
-	
+
 		File.metaClass.json = { -> new JsonSlurper().parseText(delegate.text) }
         File.metaClass.getJson = { return delegate.exists() ? new JsonSlurper().parse(delegate) : [:] }
         File.metaClass.setJson = { json -> delegate.text = new JsonBuilder(json).toPrettyString() }
-		
+
 		Date.metaClass.iso8601 = { ->
 			def format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
 			def result = format.format(delegate)
 			return result[0..21] + ':' + result[22..-1]
 		}
-        
+
         String.metaClass.rsplit = { String del, int limit = -1 ->
             def lst = new ArrayList()
             def x = 0, idx
@@ -41,7 +48,7 @@ public class Util {
             return lst
         }
 	}
-	
+
 	public static String[] getClasspath(project, libs, artifact) {
 		def ret = []
 		artifactTree(project, artifact).each { key, lib ->
@@ -51,7 +58,7 @@ public class Util {
 		}
 		return ret
 	}
-	
+
 	public static def getArtifacts(project, config, classifiers) {
 		def ret = [:]
 		config.resolvedConfiguration.resolvedArtifacts.each {
@@ -74,14 +81,6 @@ public class Util {
 			if (!checkExists(url)) {
 				url = "https://maven.minecraftforge.net/${path}"
 			}
-			//TODO remove when Mojang launcher is updated
-			if (!classifiers && art.classifier != null) { 
-				//Mojang launcher doesn't currently support classifiers, so... move it to part of the version, and force the extension to 'jar'
-				// However, keep the path normal so that our mirror system works.
-				art.version = "${art.version}-${art.classifier}"
-				art.classifier = null
-				art.extension = 'jar'
-			}
 			ret[key] = [
 				name: "${art.group}:${art.name}:${art.version}" + (art.classifier == null ? '' : ":${art.classifier}") + (art.extension == 'jar' ? '' : "@${art.extension}"),
 				downloads: [
@@ -96,14 +95,14 @@ public class Util {
 		}
 		return ret
 	}
-    
-    public static def getMavenPath(task) {        
+
+    public static def getMavenPath(task) {
         def classifier = task.archiveClassifier.get()
         def dep = "${task.project.group}:${task.project.name}:${task.project.version}" + (classifier == '' ? '' : ':' + classifier)
         return "${task.project.group.replace('.', '/')}/${task.project.name}/${task.project.version}/${task.project.name}-${task.project.version}".toString() + (classifier == '' ? '' : '-' + classifier) + '.jar'
     }
-    
-    public static def getMavenDep(task) {        
+
+    public static def getMavenDep(task) {
         def classifier = task.archiveClassifier.get()
         return "${task.project.group}:${task.project.name}:${task.project.version}" + (classifier == '' ? '' : ':' + classifier)
     }
@@ -127,7 +126,7 @@ public class Util {
 		def files = cfg.resolve()
 		return getArtifacts(project, cfg, true)
 	}
-	
+
 	private static boolean checkExists(url) {
 		try {
 			def code = new URL(url).openConnection().with {
@@ -142,4 +141,25 @@ public class Util {
 			throw e
 		}
 	}
+
+    static String getLatestForgeVersion(mcVersion) {
+        final json = new JsonSlurper().parseText(new URL('https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json').getText('UTF-8'))
+        final ver = json.promos["$mcVersion-latest"]
+        ver === null ? null : (mcVersion + '-' + ver)
+    }
+
+    static void processClassNodes(File file, Closure process) {
+        file.withInputStream { i ->
+            new ZipInputStream(i).withCloseable { zin ->
+                ZipEntry zein
+                while ((zein = zin.nextEntry) != null) {
+                    if (zein.name.endsWith('.class')) {
+                        def node = new ClassNode(ASM_LEVEL)
+                        new ClassReader(zin).accept(node, 0)
+                        process(node)
+                    }
+                }
+            }
+        }
+    }
 }

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/ValidateDeprecations.groovy

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.forge.tasks
+
+import net.minecraftforge.srgutils.MinecraftVersion
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.TaskAction
+import org.objectweb.asm.tree.AnnotationNode
+import org.objectweb.asm.tree.ClassNode
+
+abstract class ValidateDeprecations extends DefaultTask {
+    @InputFile
+    abstract RegularFileProperty getInput()
+
+    @Input
+    abstract Property<String> getMcVersion()
+
+    ValidateDeprecations() {
+        this.onlyIf { !System.env.TEAMCITY_VERSION }
+    }
+
+    @TaskAction
+    protected void exec() {
+        def mcVer = MinecraftVersion.from(mcVersion.get())
+        def errors = []
+
+        Util.processClassNodes(input.get().asFile) {
+            processNode(mcVer, errors, it)
+        }
+
+        if (!errors.isEmpty()) {
+            errors.forEach {
+                this.logger.error("Deprecated ${it[0]} is marked for removal in ${it[1]} but is not yet removed")
+            }
+            throw new IllegalStateException("Found deprecated members marked for removal but not yet removed in ${mcVer}; see log for details")
+        }
+    }
+
+    protected processNode(MinecraftVersion mcVer, List<String> errors, ClassNode node) {
+        node.visibleAnnotations?.each { annotation ->
+            ValidateDeprecations.processAnnotations(annotation, mcVer, errors) {
+                "class ${node.name}"
+            }
+        }
+        node.fields?.each { field ->
+            field.visibleAnnotations?.each { annotation ->
+                ValidateDeprecations.processAnnotations(annotation, mcVer, errors) {
+                    "field ${node.name}#${field.name}"
+                }
+            }
+        }
+        node.methods?.each { method ->
+            method.visibleAnnotations?.each { annotation ->
+                ValidateDeprecations.processAnnotations(annotation, mcVer, errors) {
+                    "method ${node.name}#${method.name}${method.desc}"
+                }
+            }
+        }
+    }
+
+    private static void processAnnotations(AnnotationNode annotation, MinecraftVersion mcVer, List<String> errors, Closure context) {
+        def values = annotation.values
+        if (values === null)
+            return
+        int forRemoval = values.indexOf('forRemoval')
+        int since = values.indexOf('since')
+        if (annotation.desc == 'Ljava/lang/Deprecated;' && forRemoval !== -1 && since !== -1 && values.size() >= 4 && values[forRemoval + 1] === true) {
+            def oldVersion = MinecraftVersion.from(values[since + 1])
+            def split = ValidateDeprecations.splitDots(oldVersion.toString())
+            if (split.length < 2)
+                return
+            def removeVersion = MinecraftVersion.from("${split[0]}.${split[1] + 1}")
+            if (removeVersion <= mcVer)
+                errors.add([context(), removeVersion])
+        }
+    }
+
+    private static int[] splitDots(String version) {
+        String[] pts = version.split('\\.')
+        int[] values = new int[pts.length]
+        for (int x = 0; x < pts.length; x++)
+            values[x] = Integer.parseInt(pts[x])
+        return values
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckATs.groovy

@@ -0,0 +1,310 @@
+package net.minecraftforge.forge.tasks.checks
+
+import groovy.transform.CompileStatic
+import groovy.transform.TupleConstructor
+import net.minecraftforge.forge.tasks.InheritanceData
+import net.minecraftforge.srgutils.IMappingFile
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.RegularFile
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.InputFiles
+import org.gradle.api.tasks.Optional
+import org.objectweb.asm.Opcodes
+
+@CompileStatic
+abstract class CheckATs extends CheckTask {
+
+    @InputFile abstract RegularFileProperty getInheritance()
+    @InputFiles abstract ConfigurableFileCollection getAts()
+    @InputFile @Optional abstract RegularFileProperty getMappings()
+
+    @Override
+    void check(Reporter reporter, boolean fix) {
+        final IMappingFile mappings = mappings.map { RegularFile it -> IMappingFile.load(it.asFile) }.getOrNull()
+        final inheritance = InheritanceData.parse(this.inheritance.get().asFile)
+
+        ats.each {
+            final lines = process(it, reporter, inheritance)
+            if (fix) {
+                it.text = joinBack(lines, inheritance, mappings).join('\n')
+            }
+        }
+    }
+
+    private static TreeMap<String, ATParser.Entry> process(File file, Reporter reporter, Map<String, InheritanceData> inheritance) {
+        final TreeMap<String, ATParser.Entry> lines = ATParser.parse(file.readLines(), reporter)
+        final Map<String, ATParser.Entry> constructorGroups = [:]
+
+        final itr = lines.entrySet().iterator()
+        final toRemove = []
+        while (itr.hasNext()) {
+            final next = itr.next()
+            String key = next.key
+            final entry = next.value
+            if (entry === null) continue
+
+            final binaryName = entry.cls.replaceAll('\\.', '/')
+
+            // Process Groups, this will remove any entries outside the group that is covered by the group
+            if (entry.group) {
+                final jcls = inheritance[binaryName]
+                if (jcls === null) {
+                    itr.remove()
+                    reporter.report("Invalid group: $key")
+                } else if ('*' == entry.desc) {
+                    if (!jcls.fields) {
+                        itr.remove()
+                        reporter.report("Invalid group, class has no fields: $key")
+                    } else {
+                        jcls.fields.each { field, value ->
+                            final fkey = entry.cls + ' ' + field
+                            if (accessLevel(value.access) < accessStr(entry.modifier)) {
+                                if (lines.containsKey(fkey)) {
+                                    toRemove.add(fkey)
+                                } else if (!entry.existing.contains(fkey)) {
+                                    reporter.report("Missing group entry: $fkey")
+                                }
+                                entry.children.add(fkey)
+                            } else if (lines.containsKey(fkey)) {
+                                toRemove.add(fkey)
+                                reporter.report("Found invalid group entry: $fkey")
+                            }
+                        }
+                        entry.existing.findAll { it !in entry.children }.each { println('Removed: ' + it) }
+                    }
+                } else if ('*()' == entry.desc) {
+                    if (!jcls.methods) {
+                        itr.remove()
+                        reporter.report("Invalid group, class has no methods: $key")
+                    } else {
+                        jcls.methods.each { mtd, value ->
+                            if (mtd.startsWith('<clinit>') || mtd.startsWith('lambda$')) return
+                            key = entry.cls + ' ' + mtd.replace(' ', '')
+                            if (accessLevel(value.access) < accessStr(entry.modifier)) {
+                                if (lines.containsKey(key)) {
+                                    toRemove.add(key)
+                                } else if (!entry.existing.contains(key)) {
+                                    reporter.report("Missing group entry: $key")
+                                }
+                                entry.children.add(key)
+                            } else if (lines.containsKey(key)) {
+                                toRemove.add(key)
+                                reporter.report("Found invalid group entry: $key")
+                            }
+                        }
+                        entry.existing.findAll { it !in entry.children }.each { println('Removed: ' + it) }
+                    }
+                } else if ('<init>' == entry.desc) { //Make all public non-abstract subclasses
+                    constructorGroups.put(binaryName, entry)
+                }
+            }
+
+            // Process normal lines, remove invalid and remove narrowing
+            else {
+                def jcls = inheritance.get(binaryName)
+                if (jcls === null) {
+                    itr.remove()
+                    reporter.report("Invalid: $key")
+                } else if (entry.desc == '') {
+                    if (accessLevel(jcls.access) > accessStr(entry.modifier) && (entry.comment === null || !entry.comment.startsWith('#force '))) {
+                        itr.remove()
+                        reporter.report("Invalid Narrowing: $key")
+                    }
+                } else if (!entry.desc.contains('(')) {
+                    if (!jcls.fields || !jcls.fields.containsKey(entry.desc)) {
+                        itr.remove()
+                        reporter.report("Invalid: $key")
+                    } else {
+                        final value = jcls.fields[entry.desc]
+                        if (accessLevel(value.access) > accessStr(entry.modifier) && (entry.comment === null || !entry.comment.startsWith('#force '))) {
+                            itr.remove()
+                            reporter.report("Invalid Narrowing: $key - ${entry.comment}")
+                        }
+                    }
+                } else {
+                    final jdesc = entry.desc.replace('(', ' (')
+                    if (!jcls.methods || !jcls.methods.containsKey(jdesc)) {
+                        itr.remove()
+                        reporter.report("Invalid: $key")
+                    } else {
+                        final value = jcls.methods[jdesc]
+                        if (accessLevel(value.access) > accessStr(entry.modifier) && (entry.comment === null || !entry.comment.startsWith('#force '))) {
+                            itr.remove()
+                            reporter.report("Invalid Narrowing: $key")
+                        }
+                    }
+                }
+            }
+        }
+
+        inheritance.each { tcls, value ->
+            if (!value.methods || ((value.access & Opcodes.ACC_ABSTRACT) !== 0)) return
+            String parent = tcls
+            while (parent !== null) {
+                constructorGroups[parent]?.tap { entry ->
+                    value.methods.each { mtd, v ->
+                        if (mtd.startsWith('<init>')) {
+                            final child = tcls.replaceAll('/', '\\.') + ' ' + mtd.replace(' ', '')
+                            if (accessLevel(v.access) < 3) {
+                                if (lines.containsKey(child)) {
+                                    toRemove.add(child)
+                                } else if (child !in entry.existing) {
+                                    reporter.report("Missing group entry: $child")
+                                }
+                                entry.children.add(child)
+                            } else if (lines.containsKey(child)) {
+                                toRemove.add(child)
+                                reporter.report("Found invalid group entry: $child")
+                            }
+                        }
+                    }
+                }
+                parent = inheritance[parent]?.superName
+            }
+        }
+        constructorGroups.values().each { entry -> entry.existing.findAll { it !in entry.children }.each{  reporter.report("Found invalid group entry: $it") } }
+
+        toRemove.each(lines.&remove)
+
+        return lines
+    }
+
+    private static List<String> joinBack(TreeMap<String, ATParser.Entry> lines, Map<String, InheritanceData> inheritance, IMappingFile mappings) {
+        final List<String> data = []
+        final remapComment = { ATParser.Entry entry ->
+            if (!mappings || !entry || !entry.desc) return null
+            final comment = entry.comment?.substring(1)?.trim()
+            final jsonCls = inheritance.get(entry.cls.replaceAll('\\.', '/'))
+            final mappingsClass = mappings?.getClass(jsonCls.name)
+            if (mappingsClass === null) return entry.comment
+            final idx = entry.desc.indexOf('(')
+
+            String mappedName = idx == -1
+                    ? mappingsClass.remapField(entry.desc)
+                    : mappingsClass.remapMethod(entry.desc.substring(0, idx), entry.desc.substring(idx))
+            if (!mappedName) return entry.comment
+            if (mappedName == '<init>')
+                mappedName = 'constructor'
+
+            if (comment?.startsWith(mappedName))
+                return '# ' + comment
+            if (comment && comment.indexOf(' ') !== -1) {
+                def split = comment.split(' - ').toList()
+                if (split[0].indexOf(' ') !== -1)
+                // The first string is more than one word, so append before it
+                    return "# ${mappedName} - ${comment}"
+                split.remove(0)
+                return "# ${mappedName} - ${String.join(' - ', split)}"
+            }
+            return '# ' + mappedName
+        }
+        lines.each { key, value ->
+            if (!value.group) {
+                def comment = remapComment.call(value)
+                data.add(value.modifier + ' ' + key + (comment ? ' ' + comment : ''))
+            } else {
+                data.add(('#group ' + value.modifier + ' ' + key + ' ' + (value.comment ?: '')).trim())
+                value.children.each {
+                    final line = value.modifier + ' ' + it
+                    final entry = ATParser.parseEntry(line)
+                    final comment = remapComment(entry)
+                    data.add(line + (comment ? ' ' + comment : ''))
+                }
+                data.add('#endgroup')
+            }
+        }
+        return data
+    }
+
+    static int accessStr(String access) {
+        if (access.endsWith('-f') || access.endsWith('+f')) return 4
+        switch (access.toLowerCase()) {
+            case 'public':    return 3
+            case 'protected': return 2
+            case 'default':   return 1
+            case 'private':   return 0
+            default:          return -1
+        }
+    }
+
+    static int accessLevel(int access) {
+        if ((access & Opcodes.ACC_PUBLIC)    !== 0) return 3
+        if ((access & Opcodes.ACC_PROTECTED) !== 0) return 2
+        if ((access & Opcodes.ACC_PRIVATE)   !== 0) return 0
+        return 1
+    }
+}
+
+@CompileStatic
+class ATParser {
+    static TreeMap<String, Entry> parse(List<String> lines, CheckTask.Reporter reporter) {
+        TreeMap<String, Entry> outLines = new TreeMap<>()
+        Entry group = null
+        for (final line : lines) {
+            if (line.isEmpty()) continue
+            if (line.startsWith('#group ')) {
+                final entry = parseEntry(line.substring(7))
+
+                if (entry.desc != '*' && entry.desc != '*()' && entry.desc != '<init>') {
+                    reporter.report("Invalid group: $line", false)
+                }
+
+                entry.group = true
+                entry.children = []
+                entry.existing = []
+
+                group = entry
+
+                if (outLines.containsKey(entry.key)) {
+                    reporter.report("Duplicate group: $line", false)
+                }
+
+                outLines[entry.key] = group
+            } else if (group !== null) {
+                if (line.startsWith('#endgroup')) {
+                    group = null
+                } else {
+                    final key = parseEntry(line).key
+                    group.existing.add(key)
+                }
+            } else if (line.startsWith('#endgroup')) {
+                reporter.report("Invalid group ending: $line", false)
+            } else if (line.startsWith('#')) {
+                //Nom
+            } else {
+                final entry = parseEntry(line)
+                if (outLines.containsKey(entry.key)) {
+                    reporter.report("Found duplicate: $line")
+                    continue
+                }
+                outLines[entry.key] = entry
+            }
+        }
+        return outLines
+    }
+
+    static Entry parseEntry(String line) {
+        final idx = line.indexOf('#')
+        final String comment = idx === -1 ? null : line.substring(idx)
+        if (idx !== -1) line = line.substring(0, idx - 1)
+        final data = (line.trim() + '     ').split(' ', -1)
+        new Entry(data[0], data[1], data[2], comment)
+    }
+
+    @TupleConstructor
+    static final class Entry {
+        String modifier, cls, desc, comment
+
+        Set<String> existing
+        TreeSet<String> children
+        boolean group = false
+
+        @Lazy
+        String key = {cls + (desc.isEmpty() ? '' : ' ' + desc)}()
+
+        Object getAt(String key) {
+            return getProperty(key)
+        }
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckExcs.groovy

@@ -0,0 +1,93 @@
+package net.minecraftforge.forge.tasks.checks
+
+import net.minecraftforge.forge.tasks.Util
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.InputFiles
+import org.objectweb.asm.ClassReader
+import org.objectweb.asm.ClassVisitor
+import org.objectweb.asm.MethodVisitor
+import org.objectweb.asm.Type
+
+import java.util.zip.ZipEntry
+import java.util.zip.ZipInputStream
+
+abstract class CheckExcs extends CheckTask {
+
+    @InputFile abstract RegularFileProperty getBinary()
+    @InputFiles abstract ConfigurableFileCollection getExcs()
+
+    @Override
+    void check(Reporter reporter, boolean fix) {
+        final Set<String> known = []
+        collectKnown(known)
+
+        excs.each { f ->
+            final lines = []
+            f.eachLine { line ->
+                def idx = line.indexOf('#')
+                if (idx == 0 || line.isEmpty()) {
+                    return
+                }
+
+                if (idx != -1) line = line.substring(0, idx - 1)
+
+                if (!line.contains('=')) {
+                    reporter.report("Invalid: $line")
+                    return
+                }
+
+                def (String key, String value) = line.split('=', 2)
+                if (!known.contains(key)) {
+                    reporter.report("Unknown: $line")
+                    return
+                }
+
+                String desc = key.split('\\.', 2)[1]
+                if (!desc.contains('(')) {
+                    reporter.report("Invalid: $line")
+                    return
+                }
+                desc = '(' + desc.split('\\(', 2)[1]
+
+                def (exceptions, String args) = value.contains('|') ? value.split('|', 2) : [value, '']
+
+                if (args.split(',').length !== Type.getArgumentTypes(desc).length) {
+                    reporter.report("Invalid: $line")
+                    return
+                }
+                lines.add(line)
+            }
+
+            if (fix) f.text = lines.sort().join('\n')
+        }
+    }
+
+    private void collectKnown(Collection<String> known) {
+        binary.get().asFile.withInputStream { i ->
+            new ZipInputStream(i).withCloseable { zin ->
+                final visitor = new ClassVisitor(Util.ASM_LEVEL) {
+                    private String cls
+                    @Override
+                    void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
+                        this.cls = name
+                    }
+
+                    @Override
+                    MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
+                        known.add(this.cls + '.' + name + descriptor)
+                        super.visitMethod(access, name, descriptor, signature, exceptions)
+                    }
+                }
+                ZipEntry zein
+                while ((zein = zin.nextEntry) !== null) {
+                    if (zein.name.endsWith('.class')) {
+                        ClassReader reader = new ClassReader(zin)
+                        reader.accept(visitor, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES)
+                    }
+                }
+            }
+        }
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckMode.groovy

@@ -0,0 +1,9 @@
+package net.minecraftforge.forge.tasks.checks
+
+import groovy.transform.CompileStatic
+
+@CompileStatic
+enum CheckMode {
+    CHECK,
+    FIX
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckPatches.groovy

@@ -0,0 +1,182 @@
+package net.minecraftforge.forge.tasks.checks
+
+import groovy.transform.CompileStatic
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.provider.ListProperty
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputDirectory
+import org.gradle.api.tasks.Optional
+
+import java.nio.file.Files
+import java.nio.file.Path
+import java.util.regex.Pattern
+
+@CompileStatic
+abstract class CheckPatches extends CheckTask {
+
+    private static final Pattern HUNK_START_PATTERN = Pattern.compile('^@@ -[0-9,]* \\+[0-9,_]* @@$')
+    private static final Pattern WHITESPACE_PATTERN = Pattern.compile('^[+\\-]\\s*$')
+    private static final Pattern IMPORT_PATTERN = Pattern.compile('^[+\\-]\\s*import.*')
+    private static final Pattern FIELD_PATTERN = Pattern.compile('^[+\\-][\\s]*((public|protected|private)[\\s]*)?(static[\\s]*)?(final)?([^=;]*)(=.*)?;\\s*$')
+    private static final Pattern METHOD_PATTERN = Pattern.compile('^[+\\-][\\s]*((public|protected|private)[\\s]*)?(static[\\s]*)?(final)?([^(]*)[(]([^)]*)?[)]\\s*[{]\\s*$')
+    private static final Pattern CLASS_PATTERN = Pattern.compile('^[+\\-][\\s]*((public|protected|private)[\\s]*)?(static[\\s]*)?(final[\\s]*)?(class|interface)([^{]*)[{]\\s*$')
+    private static final Map<String, Integer> ACCESS_MAP = [private: 0, protected: 2, public: 3].tap { it.put(null, 1) }
+
+    @InputDirectory abstract DirectoryProperty getPatchDir()
+    @Input @Optional abstract ListProperty<String> getPatchesWithS2SArtifact()
+
+    @Override
+    void check(Reporter reporter, boolean fix) {
+        final patchDir = getPatchDir().get().asFile.toPath()
+        Files.walk(patchDir).withCloseable {
+            it.filter(Files.&isRegularFile).forEach { path ->
+                final String relativeName = patchDir.relativize(path).toString()
+                verifyPatch(path, reporter, fix, relativeName, patchesWithS2SArtifact.get().contains(relativeName.replace('\\', '/')))
+            }
+        }
+    }
+    
+    def accessChange(previous, current) {
+        //return ACCESS_MAP[previous] < ACCESS_MAP[current]
+        return previous != current
+    }
+
+    void verifyPatch(Path patch, Reporter reporter, boolean fix, String patchPath, boolean hasS2SArtifact) {
+        final oldFixedErrors = reporter.fixed.size()
+
+        final lines = Files.readAllLines(patch)
+
+        int hunksStart = 0
+        boolean onlyWhiteSpace = false
+
+        final List<String> newLines = []
+
+        // First two lines are file name ++/-- and we do not care
+        newLines.add(lines[0] + '\n')
+        newLines.add(lines[1] + '\n')
+
+        int i
+        for (i = 2; i < lines.size(); ++i) {
+            def line = lines[i]
+            newLines.add(line + '\n')
+
+            if (HUNK_START_PATTERN.matcher(line).find()) {
+                if (onlyWhiteSpace) {
+                    if (!hasS2SArtifact)
+                        reporter.report("Patch contains only white space hunk starting at line ${hunksStart + 1}, file: $patchPath")
+                    int toRemove = i - hunksStart
+                    while (toRemove-- > 0)
+                        newLines.remove(newLines.size() - 1)
+                }
+                hunksStart = i
+                onlyWhiteSpace = true
+                continue
+            }
+
+            if (line.startsWithAny('+','-')) {
+                def prefixChange = false
+                def prevLine = lines[i - 1]
+
+                if (line.charAt(0) == (char)'+' && prevLine.charAt(0) == (char)'-') {
+                    def prevTrim = prevLine.substring(1).replaceAll("\\s", "")
+                    def currTrim = line.substring(1).replaceAll("\\s", "")
+
+                    if (prevTrim == currTrim) {
+                        prefixChange = true
+                    }
+
+                    def pMatcher = FIELD_PATTERN.matcher(prevLine)
+                    def cMatcher = FIELD_PATTERN.matcher(line)
+
+                    if (pMatcher.find() && cMatcher.find() &&
+                            pMatcher.group(6) == cMatcher.group(6) && // = ...
+                            pMatcher.group(5) == cMatcher.group(5) && // field name
+                            pMatcher.group(3) == cMatcher.group(3) && // static
+                            (accessChange(pMatcher.group(2), cMatcher.group(2)) || pMatcher.group(4) != cMatcher.group(4))) {
+                        reporter.report("Patch contains access changes or final removal at line ${i + 1}, file: $patchPath", false)
+                    }
+
+                    pMatcher = METHOD_PATTERN.matcher(prevLine)
+                    cMatcher = METHOD_PATTERN.matcher(line)
+
+                    if (pMatcher.find() && cMatcher.find() &&
+                            pMatcher.group(6) == cMatcher.group(6) && // params
+                            pMatcher.group(5) == cMatcher.group(5) && // <T> void name
+                            pMatcher.group(3) == cMatcher.group(3) && // static
+                            (accessChange(pMatcher.group(2), cMatcher.group(2)) || pMatcher.group(4) != cMatcher.group(4))) {
+                        reporter.report("Patch contains access changes or final removal at line ${i + 1}, file: $patchPath", false)
+                    }
+
+                    pMatcher = CLASS_PATTERN.matcher(prevLine)
+                    cMatcher = CLASS_PATTERN.matcher(line)
+
+                    if (pMatcher.find() && cMatcher.find() &&
+                            pMatcher.group(6) == cMatcher.group(6) && // ClassName<> extends ...
+                            pMatcher.group(5) == cMatcher.group(5) && // class | interface
+                            pMatcher.group(3) == cMatcher.group(3) && // static
+                            (accessChange(pMatcher.group(2), cMatcher.group(2)) || pMatcher.group(4) != cMatcher.group(4))) {
+                        reporter.report("Patch contains access changes or final removal at line ${i + 1}, file: $patchPath", false)
+                    }
+                }
+
+                if (line.charAt(0) == (char)'-' && i + 1 < lines.size()) {
+                    final nextLine = lines[i + 1]
+                    if (nextLine.charAt(0) == (char)'+') {
+                        final nextTrim = nextLine.substring(1).replaceAll("\\s", "")
+                        final currTrim = line.substring(1).replaceAll("\\s", "")
+
+                        if (nextTrim == currTrim) {
+                            prefixChange = true
+                        }
+                    }
+                }
+
+                final isWhiteSpaceChange = WHITESPACE_PATTERN.matcher(line).find()
+
+                if (!prefixChange && !isWhiteSpaceChange) {
+                    onlyWhiteSpace = hasS2SArtifact && IMPORT_PATTERN.matcher(line).find()
+                } else if (isWhiteSpaceChange) {
+                    final prevLineChange = prevLine.startsWithAny('+','-')
+                    final nextLineChange = i + 1 < lines.size() && lines[i + 1].startsWithAny('+','-')
+
+                    if (!prevLineChange && !nextLineChange) {
+                        reporter.report("Patch contains white space change in valid hunk at line ${i + 1}, file: $patchPath", false)
+                    }
+                }
+
+                if (line.contains('\t')) {
+                    reporter.report("Patch contains tabs on line ${i + 1}, file: $patchPath")
+                    line = line.replaceAll('\t', '    ')
+                    newLines.remove(newLines.size() - 1)
+                    newLines.add(line + '\n')
+                }
+
+                if (IMPORT_PATTERN.matcher(line).find() && !hasS2SArtifact) {
+                    reporter.report("Patch contains import change on line ${i + 1}, file: $patchPath", false)
+                }
+            }
+        }
+
+        if (onlyWhiteSpace) {
+            if (!hasS2SArtifact)
+                reporter.report("Patch contains only white space hunk starting at line ${hunksStart + 1}, file: $patchPath")
+            def toRemove = i - hunksStart;
+            while (toRemove-- > 0)
+                newLines.remove(newLines.size() - 1)
+        }
+
+        if ((reporter.fixed.size() > oldFixedErrors && fix) || hasS2SArtifact) {
+            if (newLines.size() <= 2) {
+                logger.lifecycle("Patch is now empty removing, file: {}", patchPath)
+                Files.delete(patch)
+            }
+            else {
+                if (!hasS2SArtifact)
+                    logger.lifecycle("*** Updating patch file. Please run setup then genPatches again. ***")
+                Files.newBufferedWriter(patch).withCloseable {
+                    newLines.each { l -> it.write(l) }
+                }
+            }
+        }
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckSAS.groovy

@@ -0,0 +1,110 @@
+package net.minecraftforge.forge.tasks.checks
+
+import groovy.transform.CompileStatic
+import net.minecraftforge.forge.tasks.Annotatable
+import net.minecraftforge.forge.tasks.InheritanceData
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.InputFiles
+
+@CompileStatic
+abstract class CheckSAS extends CheckTask {
+
+    @InputFile abstract RegularFileProperty getInheritance()
+    @InputFiles abstract ConfigurableFileCollection getSass()
+
+    @Override
+    void check(Reporter reporter, boolean fix) {
+        final inheritance = InheritanceData.parse(this.inheritance.get().asFile)
+
+        sass.each { f ->
+            final lines = []
+            f.eachLine { line ->
+                if (line[0] == '\t') return // Skip any tabbed lines, those are ones we add
+                final idx = line.indexOf('#')
+                if (idx == 0 || line.isEmpty()) {
+                    lines.add(line)
+                    return
+                }
+                def comment = idx == -1 ? null : line.substring(idx)
+                if (idx != -1) line = line.substring(0, idx - 1)
+                final spl = (line.trim().replace('(', ' (') + '     ').split(' ', -1)
+                def (String cls, String name, String desc) = [spl[0], spl[1], spl[2]]
+                cls = cls.replaceAll('\\.', '/')
+
+                if (inheritance[cls] === null) {
+                    reporter.report("Invalid: $line")
+                } else if (name.isEmpty()) { //Class SAS
+                    final toAdd = []
+                    final clsSided = isSided(inheritance[cls])
+                    boolean sided = clsSided
+
+                    /* TODO: MergeTool doesn't do fields
+                    if (json[cls]['fields'] != null) {
+                        for (entry in json[cls]['fields']) {
+                            if (isSided(entry.value)) {
+                                sided = true
+                                toAdd.add('\t' + cls + ' ' + entry.key)
+                            }
+						}
+                    } */
+
+                    final clsInh = inheritance[cls]
+                    if (clsInh.methods) {
+                        for (entry in clsInh.methods) {
+                            if (isSided(entry.value)) {
+                                sided = true
+                                toAdd.add('\t' + cls + ' ' + entry.key.replaceAll(' ', ''))
+                                findChildMethods(inheritance, cls, entry.key).each { lines.add('\t' + it) }
+                                findChildMethods(inheritance, cls, entry.key).each { println(line + ' -- ' + it) }
+                            } else if (clsSided) {
+                                findChildMethods(inheritance, cls, entry.key).each { lines.add('\t' + it) }
+                                findChildMethods(inheritance, cls, entry.key).each { println(line + ' -- ' + it) }
+                            }
+                        }
+                    }
+
+                    if (sided) {
+                        lines.add(cls + (comment == null ? '' : ' ' + comment))
+                        lines.addAll(toAdd.sort())
+                    } else {
+                        reporter.report("Invalid: $line")
+                    }
+
+                } else if (desc.isEmpty()) { // Fields
+                    /* TODO: MergeTool doesn't do fields
+                    if (json[cls]['fields'] != null && isSided(json[cls]['fields'][name]))
+                        lines.add(cls + ' ' + name + (comment == null ? '' : ' ' + comment))
+                    else */
+                    reporter.report("Invalid: $line")
+                } else { // Methods
+                    final clsInh = inheritance[cls]
+                    if (clsInh.methods === null || !isSided(clsInh.methods[name + ' ' + desc]))
+                        reporter.report("Invalid: $line")
+                    else {
+                        lines.add(cls + ' ' + name + desc + (comment == null ? '' : ' ' + comment))
+                        findChildMethods(inheritance, cls, name + ' ' + desc).each { println(line + ' -- ' + it) }
+                        findChildMethods(inheritance, cls, name + ' ' + desc).each { lines.add('\t' + it) }
+                    }
+                }
+            }
+
+            if (fix) f.text = lines.join('\n')
+        }
+    }
+
+    protected static isSided(Annotatable annotatable) {
+        if (annotatable === null) return false
+        for (ann in annotatable.annotations) {
+            if ('Lnet/minecraftforge/api/distmarker/OnlyIn;' == ann.desc)
+                return true
+        }
+        return false
+    }
+    
+    protected static findChildMethods(Map<String, InheritanceData> json, String cls, String desc) {
+        return json.values().findAll{ it.methods != null && it.methods[desc] != null && it.methods[desc].override == cls && isSided(it.methods[desc]) }
+                .collect { it.name + ' ' + desc.replace(' ', '') } as TreeSet
+    }
+}

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckTask.groovy

@@ -0,0 +1,111 @@
+package net.minecraftforge.forge.tasks.checks
+
+import groovy.transform.CompileStatic
+import net.minecraftforge.forge.tasks.Util
+import org.gradle.api.Action
+import org.gradle.api.DefaultTask
+import org.gradle.api.logging.LogLevel
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.TaskAction
+import org.gradle.api.tasks.TaskContainer
+import org.gradle.api.tasks.VerificationTask
+
+@CompileStatic
+abstract class CheckTask extends DefaultTask implements VerificationTask {
+    @Input
+    abstract Property<CheckMode> getMode()
+
+    private boolean ignoreFailures = false
+
+    @Input
+    @Override
+    boolean getIgnoreFailures() {
+        return ignoreFailures
+    }
+
+    @Override
+    void setIgnoreFailures(boolean ignoreFailures) {
+        this.ignoreFailures = ignoreFailures
+    }
+
+    @TaskAction
+    void run() {
+        Util.init()
+
+        final doFix = getMode().get() === CheckMode.FIX
+        final Reporter reporter = new Reporter(doFix)
+        check(reporter, doFix)
+        
+        if (reporter.messages) {
+            if (getMode().get() === CheckMode.CHECK) {
+                logger.error("Check task '{}' found errors:\n{}", name, reporter.messages.join('\n'))
+                if (!ignoreFailures) {
+                    throw new IllegalArgumentException("${reporter.messages.size()} errors were found!")
+                }
+            } else {
+                if (logger.isEnabled(LogLevel.DEBUG)) {
+                    logger.warn("Check task '{}' found {} errors and fixed {}:\n{}", name, reporter.messages.size(), reporter.fixed.size(), reporter.fixed.join('\n'))
+                } else {
+                    logger.warn("Check task '{}' found {} errors and fixed {}.", name, reporter.messages.size(), reporter.fixed.size())
+                }
+
+                if (reporter.notFixed) {
+                    logger.error('{} errors could not be fixed:\n{}', reporter.notFixed.size(), reporter.notFixed.join('\n'))
+                    if (!ignoreFailures) {
+                        throw new IllegalArgumentException("${reporter.notFixed.size()} errors which cannot be fixed were found!")
+                    }
+                }
+            }
+        }
+    }
+
+    abstract void check(Reporter reporter, boolean fix)
+
+    @CompileStatic
+    static final class Reporter {
+        final boolean trackFixed
+        Reporter(boolean trackFixed) {
+            this.trackFixed = trackFixed
+        }
+
+        public final List<String> messages = []
+
+        public final List<String> fixed = []
+        public final List<String> notFixed = []
+
+        void report(String message, boolean canBeFixed = true) {
+            messages.add(message)
+
+            if (trackFixed) {
+                if (canBeFixed) {
+                    fixed.add(message)
+                } else {
+                    notFixed.add(message)
+                }
+            }
+        }
+    }
+
+    static <T extends CheckTask> void registerTask(TaskContainer tasks, String taskName, @DelegatesTo.Target('type') Class<T> clazz,
+                                                   @DelegatesTo(genericTypeIndex = 0, target = 'type') Closure configuration) {
+        taskName = taskName.capitalize()
+        tasks.register("check$taskName", clazz) { CheckTask task ->
+            def castedTask = task as T
+            configuration.setDelegate(castedTask)
+            configuration.call(castedTask)
+            castedTask.mode.set(CheckMode.CHECK)
+            castedTask.group = 'checks'
+        }
+        tasks.named('checkAll').configure { it.dependsOn("check$taskName") }
+
+        tasks.register("checkAndFix$taskName", clazz) { CheckTask task ->
+            def castedTask = task as T
+            configuration.setDelegate(castedTask)
+            configuration.call(castedTask)
+            castedTask.mode.set(CheckMode.CHECK)
+            castedTask.group = 'checks'
+        }
+        tasks.named('checkAllAndFix').configure { it.dependsOn("checkAndFix$taskName") }
+    }
+}

docs/CONTRIBUTING.md

@@ -1,13 +1,13 @@
 Contributing to Forge
 =====================
 
-1) Keep patches to Minecraft classes minimal. If you need a lot of things done, you may either add to relevant forge classes or make a new class.
+1) Keep patches to Minecraft classes together. If you need a lot of things done, you may either add to relevant forge classes or make a new class. Try not to spread out your patches across multiple disjoint lines, as this makes maintenance of your patches difficult.
 
-2) An example mod must be provided for all PRs adding events/hooks to Forge. Whether it's a full mod using your proposed hooks, or just a pastebin containing a simple example, an example mod is required. Please also explain in detail what your new hook does.
+2) TODO: Test Mods
 
-3) Follow Forge coding guidelines (braces on newlines, spaces instead of tabs, etc)
+3) Follow the code style of the class you're working in (braces on newlines & spaces instead of tabs in Forge classes, inline brackets in patches, etc).
 
-For more information, refer to [the wiki](https://github.com/MinecraftForge/MinecraftForge/wiki/If-you-want-to-contribute-to-Forge)
+For more information, refer to [the wiki][Wiki].
 
 
 Contributor License Agreement
@@ -16,3 +16,5 @@ Contributor License Agreement
 - You assign copyright ownership of your contributions to the patches codebase (everything under patches) to Forge, where it will be licensed under the LGPLv2.1 license.
 
 "Forge" is Forge Development LLC, a legally incorporated entity in Oregon, USA.
+
+[Wiki]: https://github.com/MinecraftForge/MinecraftForge/wiki/If-you-want-to-contribute-to-Forge

docs/README.md

@@ -2,16 +2,15 @@
 
 MinecraftForge
 =============
-[![Stable Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Stable&prefix=1.18.2-&query=$.promos["1.18.2-recommended"]&color=brightgreen&logo=data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPHN2ZyBjbGFzcz0ic3ZnLWlubGluZS0tZmEgZmEtc3RhciBmYS13LTE4IiBhcmlhLWhpZGRlbj0idHJ1ZSIgZGF0YS1pY29uPSJzdGFyIiBkYXRhLXByZWZpeD0iZmFzIiBmb2N1c2FibGU9ImZhbHNlIiByb2xlPSJpbWciIHZpZXdCb3g9IjAgMCA1NzYgNTEyIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPgo8cGF0aCBkPSJNMjU5LjMgMTcuOEwxOTQgMTUwLjIgNDcuOSAxNzEuNWMtMjYuMiAzLjgtMzYuNyAzNi4xLTE3LjcgNTQuNmwxMDUuNyAxMDMtMjUgMTQ1LjVjLTQuNSAyNi4zIDIzLjIgNDYgNDYuNCAzMy43TDI4OCA0MzkuNmwxMzAuNyA2OC43YzIzLjIgMTIuMiA1MC45LTcuNCA0Ni40LTMzLjdsLTI1LTE0NS41IDEwNS43LTEwM2MxOS0xOC41IDguNS01MC44LTE3LjctNTQuNkwzODIgMTUwLjIgMzE2LjcgMTcuOGMtMTEuNy0yMy42LTQ1LjYtMjMuOS01Ny40IDB6IiBmaWxsPSJ3aGl0ZSIvPgo8L3N2Zz4K)](https://files.minecraftforge.net)
-[![Latest Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Latest&prefix=1.18.2-&query=$.promos["1.18.2-latest"]&color=blue&logo=data:image/svg+xml;base64,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
-)](https://files.minecraftforge.net) [![Discord](https://img.shields.io/discord/313125603924639766.svg?color=%237289da&label=Discord&logo=discord&logoColor=%237289da)](https://discord.gg/UvedJ9m) [![Support](https://img.shields.io/badge/Patreon-Support-orange.svg?logo=Patreon)](https://www.patreon.com/LexManos)
+[![Stable Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Stable&prefix=1.19.4-&query=$.promos["1.19.4-recommended"]&color=brightgreen&logo=data:image/svg+xml;base64,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)][Download]
+[![Latest Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Latest&prefix=1.19.4-&query=$.promos["1.19.4-latest"]&color=blue&logo=data:image/svg+xml;base64,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
+)][Download] [![Discord](https://img.shields.io/discord/313125603924639766.svg?color=%237289da&label=Discord&logo=discord&logoColor=%237289da)][Discord] [![Support](https://img.shields.io/badge/Patreon-Support-orange.svg?logo=Patreon)][Patreon]
 
 Forge is a free, open-source modding API all of your favourite mods use!
 
-|    Version    |    Support    |
-| ------------- | ------------- |
-|    1.18.x     |    Active     |
-|    1.16.x     |    LTS        |
+| Version      | Support                     |
+|--------------|-----------------------------|
+| All versions | [Supported][Support-Policy] |
 
 * [Download]
 * [Forum]
@@ -20,7 +19,7 @@ Forge is a free, open-source modding API all of your favourite mods use!
 
 # Installing Forge
 
-Go to [the Forge website](https://files.minecraftforge.net)
+Go to [the Forge website][Download]
  and select the Minecraft version you wish to get Forge for from the list.
 
 You can download the installer for the *Recommended Build* or the
@@ -29,37 +28,68 @@ You can download the installer for the *Recommended Build* or the
  into your vanilla launcher environment, where you can then create a new
  profile using that version and play the game!
  
-For support and questions, visit [the Support Forum](https://www.minecraftforge.net/forum/forum/18-support-bug-reports/).
+For support and questions, visit [the Support Forum][Support-Forum] or [the Forge Discord server][Discord].
 
-[Here is a short video from Rorax showing how to install and setup Forge.](https://www.youtube.com/watch?v=lB3ArN_-3Oc)
+## Required Java Versions
+
+We require the version of Java that Minecraft requires, which is currently:
+
+| Minecraft     | Java              |
+|---------------|-------------------|
+| 1.20.6+       | [21][Adoptium-21] |
+| 1.18 - 1.20.4 | [17][Adoptium-17] |
+| 1.17.1        | [16][Adoptium-16] |
+| 1.16.5-       | [8][Adoptium-8]   |
+
+**If you are on Windows and have difficulty using Java to launch JAR files, consider using [Jarfix by Johann Löfflmann][Jarfix].**
 
 # Creating Mods
 
-[See the "Getting Started" section in the Forge Documentation](https://mcforge.readthedocs.io/en/latest/gettingstarted/).
+[See the "Getting Started" section in the Forge Documentation][Getting-Started].
 
 # Contribute to Forge
 
 If you wish to actually inspect Forge, submit PRs or otherwise work
  with Forge itself, you're in the right place!
- 
- [See the guide to setting up a Forge workspace](http://mcforge.readthedocs.io/en/latest/forgedev/).
+
+ [See the guide to setting up a Forge workspace][ForgeDev].
 
 ### Pull requests
 
-[See the "Making Changes and Pull Requests" section in the Forge documentation](https://mcforge.readthedocs.io/en/latest/forgedev/#making-changes-and-pull-requests).
+[See the "Making Changes and Pull Requests" section in the Forge documentation][Pull-Requests].
 
-Please read the contributing guidelines found [here](CONTRIBUTING.md) before making a pull request.
+Please read the contributing guidelines found [here][Contributing] before making a pull request.
 
 ### Contributor License Agreement
-We require all contributors to acknowledge the [Forge Contributor
- License Agreement](https://cla-assistant.io/MinecraftForge/MinecraftForge). Please ensure you have a valid email address
- associated with your GitHub account to do this. If you have previously
+We require all contributors to acknowledge the [Forge Contributor License Agreement][CLA]. 
+Please ensure you have a valid email address associated with your GitHub account to do this. If you have previously 
  signed it, you should be OK.
 
 #### Donate
-*Forge is a large project with many collaborators working on it around the clock. Forge is and will always remain free to use and modify. However, it costs money to run such a large project as this, so please consider [becoming a patron](https://www.patreon.com/LexManos).*
+*Forge is a large project with many collaborators working on it around the clock. Forge is and will always remain free 
+ to use and modify. However, it costs money to run such a large project as this, so please consider 
+ [becoming a patron][Patreon].*
+
+[Contributing]: ./CONTRIBUTING.md
+[CLA]: https://cla-assistant.io/MinecraftForge/MinecraftForge
 
 [Download]: https://files.minecraftforge.net/
-[Forum]: https://www.minecraftforge.net/forum/
-[Discord]: https://discord.gg/UvedJ9m
-[Documentation]: https://mcforge.readthedocs.io
+
+[Adoptium-21]: https://adoptium.net/temurin/releases/?version=21
+[Adoptium-17]: https://adoptium.net/temurin/releases/?version=17
+[Adoptium-16]: https://adoptium.net/temurin/releases/?version=16
+[Adoptium-8]: https://adoptium.net/temurin/releases/?version=8
+[Jarfix]: https://johann.loefflmann.net/en/software/jarfix/index.html
+
+[Forum]: https://forums.minecraftforge.net/
+[Support-Forum]: https://forums.minecraftforge.net/forum/18-support-bug-reports/
+[Support-Policy]: https://forums.minecraftforge.net/topic/144690-new-tiered-support-policy
+
+[Discord]: https://discord.minecraftforge.net/
+
+[Documentation]: https://docs.minecraftforge.net/en/1.19.x/
+[Getting-Started]: https://docs.minecraftforge.net/en/1.19.x/gettingstarted/
+[ForgeDev]: https://docs.minecraftforge.net/en/1.19.x/forgedev/
+[Pull-Requests]: https://docs.minecraftforge.net/en/1.19.x/forgedev/#making-changes-and-pull-requests
+
+[Patreon]: https://www.patreon.com/LexManos

docs/SUPPORT.md

@@ -1,7 +1,7 @@
 Getting Support Surrounding Forge
 =================================
 
-**If you do not want to read the following wall of text, no matter its relevance for helping get your issue resolved quickly, please refer to the [Forge Forums](http://www.minecraftforge.net/forum/forum/18-support-bug-reports/) for support.**
+**If you do not want to read the following wall of text, no matter its relevance for helping get your issue resolved quickly, please refer to the [Forge Forums][Bug-Reports] for support.**
 
 Before reporting an issue on this repository's bug tracker, please carefully read this document. There are various resources that are more likely to be able to help you with certain kinds of issues. This document provides instructions on how to determine which place best to report to.
 
@@ -44,7 +44,7 @@ You can generally tell pretty quickly what caused the error at the head of your
  1. If you can find the name of a mod in the trace, that mod most likely is the culprit.
     - Be aware that you may find multiple mods as participants of a crash. In that case, you can either report to both or try to reason (using the names in the stacktrace) about which mod is at fault.
  2. If you can only find Forge (usually starting with `net.minecraftforge`) alongside Vanilla (usually starting with `net.minecraft`) references, chances are that you have found a bug in Forge. In this case, use one of the various [support channels](#forge-support) listed below.
-    - The occurence of a single call to Forge somewhere in the stacktrace *does not* warrant a report to Forge if there are mods present in the crash report.
+    - The occurrence of a single call to Forge somewhere in the stacktrace *does not* warrant a report to Forge if there are mods present in the crash report.
  3. If there's no mention of Forge or a mod, but any Vanilla class, you might have found a Vanilla bug. You should probably still report it via the Forge channels first, however, due the nature of modded environments and the rarity of Vanilla crash bugs.
  4. Always check whether there's a mention of coremods at the beginning of a crash report. If there is and you can't find any clear culprit, consider reporting to these coremods first, since they are free to change any of the code executed in your environment.
 
@@ -74,17 +74,18 @@ Please note that this list has to be considered incomplete as there is a large n
 
 If you're certain you've found an issue that is directly caused by Forge, you have the following three platforms available for dealing with it, with decreasing relevance for end-users:
 
- 1. **Forge Forums:** There's a dedicated [Support & Bug Report](http://www.minecraftforge.net/forum/forum/18-support-bug-reports/) section on the Forge forums, which is led by team of moderators and volunteers who will try to deal with your reports as quickly as possible. *As a player you should probably report here first.*
-   - For modders, there also is a separate [Modder Support](http://www.minecraftforge.net/forum/forum/70-modder-support/) section where you can ask all your development-related questions. *You should prefer this section for coding help.*
- 2. **Forge IRC Channel:** You can find a lot of help on the official [`#minecraftforge`](irc://irc.esper.net:6667/minecraftforge) channel on EsperNet. Especially smaller issues that you quickly need help with could be reported there. *Be aware that the channel is more suited towards development questions, so while you may get support there as a player, you should almost always prefer the forums.*
- 3. **Forge Issue Tracker:** If you're absolutely certain that you've found an issue in the Forge codebase (e.g. you're a modder yourself and have analyzed the stacktrace and relevant code), don't refrain from reporting it on this repository's [issue tracker](https://github.com/MinecraftForge/MinecraftForge/issues). *Please do not use the issues as a means of getting coding help. For developers, the IRC and the [official documentation](https://mcforge.readthedocs.io) are the best sources of information.*
+ 1. **Forge Forums:** There's a dedicated [Support & Bug Report][Bug-Reports] section on the Forge forums, which is led by team of moderators and volunteers who will try to deal with your reports as quickly as possible. *As a player you should probably report here first.*
+   - For modders, there also is a separate [Modder Support][Modder-Support] section where you can ask all your development-related questions. *You should prefer this section for coding help.*
+ 2. **Forge Discord Server:** You can find a lot of help on the official [Discord Server][Discord], especially smaller issues that you quickly need help with. *Be aware that the channel is more suited towards development questions, so while you may get support there as a player, you should almost always prefer the forums.*
+ 3. **Forge Issue Tracker:** If you're absolutely certain that you've found an issue in the Forge codebase (e.g. you're a modder yourself and have analyzed the stacktrace and relevant code), don't refrain from reporting it on this repository's [issue tracker](https://github.com/MinecraftForge/MinecraftForge/issues). *Please do not use the issues as a means of getting coding help. For developers, the IRC and the [official documentation][Documentation] are the best sources of information.*
 
 ### Mod Support
 
 A lot of mods also use GitHub or other source management systems and their integrated issue trackers. The following options will give you the best chances of reporting your issue in the right place:
 
  - **CurseForge:** Many mods are hosted on the [CurseForge platform](https://minecraft.curseforge.com) nowadays. Chances are you already downloaded them from there or as a part of a modpack hosted there. Projects may specify an issue reporting link on their own page, so simply look for it on the mod's project page and you should be directed to the preferred means of error reporting.
- - **Searching for a repository directly:** You may need to try and find a repository directly on source control sites. The most common ones are [GitHub](https://github.com) and [BitBucket](https://bitbucket.org). Both come with search capabilities, so simply try to search for the mod's name.
+ - **Modrinth:** Some modders use [Modrinth](https://modrinth.com/mods) to host their mods, but be mindful that not all mods on this platform are for the Forge modloader.
+ - **Searching for a repository directly:** You may need to try and find a repository directly on source control sites. The most common ones are [GitHub](https://github.com), [GitLab](https://gitlab.com), and [BitBucket](https://bitbucket.org). Both come with search capabilities, so simply try to search for the mod's name.
 
 ### Vanilla Support
 
@@ -98,7 +99,7 @@ Now that you've identified the source of your issue and decided on the correct s
 ### Preventing Duplicates and Unnecessary Reports
 Use the target issue tracker's search functionality to look for issues which have descriptions similar to yours, but make sure to also search for already closed issues. If you can find one, verify it is in fact the same (or a very similar issue) and simply comment on it if you have anything else to contribute to the discussion, such as other steps to reproduce it. *Do not create duplicates of an existing issue, since it only puts extra effort on maintainers to recognize and close/mark them.*
 
-Additionally, always check the *latest* changelogs of Forge and participating mods to find out if the bug was already noticed and fixed by the developer. Often the maintainer may only support newer versions of the game, so also check the changelogs for versions of Minecraft you don't actually actively play. If the issue was adressed already, *do not report it*, even if the fix only exists for a newer version of the game, since the developer probably had a good reason to do so. If your issue only exists with versions of a mod that are for very old versions of the game, also refrain from reporting them, considering most modders only support the two latest versions of Minecraft, if at all.
+Additionally, always check the *latest* changelogs of Forge and participating mods to find out if the bug was already noticed and fixed by the developer. Often the maintainer may only support newer versions of the game, so also check the changelogs for versions of Minecraft you don't actually actively play. If the issue was addressed already, *do not report it*, even if the fix only exists for a newer version of the game, since the developer probably had a good reason to do so. If your issue only exists with versions of a mod that are for very old versions of the game, also refrain from reporting them, considering most modders only support the two latest versions of Minecraft, if at all.
 
 ### Required Information
 If you're certain that your issue went unnoticed up until now, you can get to actually writing up the report. Below you can find a list of the *required* information any bug report should contain:
@@ -143,4 +144,11 @@ After you have written your bug report, it is time to *wait*. Please be *patient
 
 Every project has a different way of dealing with issues, so don't wonder if there's no comment on it, but somebody "labels" it with certain markers. This helps developers to more easily keep track of bugs and priorities. When any further input from you is required, you will be asked specifically. Do not bug anyone through other channels about resolving your issue.
 
-Once your issue is closed, you will know whether it was valid or turned out to be irreproducible. If you included all of the data from above in your report, chances are that the latter won't be the case.
+Once your issue is closed, you will know whether it was valid or turned out to be unreproducible. If you included all of the data from above in your report, chances are that the latter won't be the case.
+
+[Bug-Reports]: https://forums.minecraftforge.net/forum/18-support-bug-reports/
+[Modder-Support]: https://forums.minecraftforge.net/forum/70-modder-support/
+
+[Discord]: https://discord.minecraftforge.net/
+
+[Documentation]: https://docs.minecraftforge.net/

fmlcore/build.gradle

@@ -10,10 +10,12 @@ apply plugin: 'org.javamodularity.moduleplugin'
 dependencyUpdates.rejectVersionIf { isNonStable(it.candidate.version) }
 
 dependencies {
-    compileOnly('org.jetbrains:annotations:21.0.1')
+    compileOnly("org.jetbrains:annotations:${JETBRAINS_ANNOTATIONS_VERSION}")
+
+    api("net.minecraftforge:eventbus:${EVENTBUS_VERSION}")
+
     implementation(project(':fmlloader'))
-    api('net.minecraftforge:eventbus:5.0.+')
-    implementation('commons-io:commons-io:2.5')
+    implementation("commons-io:commons-io:${COMMONS_IO_VERSION}")
 }
 
 task sourcesJar(type: Jar) {

fmlcore/src/main/java/net/minecraftforge/fml/Bindings.java

@@ -5,36 +5,36 @@
 
 package net.minecraftforge.fml;
 
-import cpw.mods.modlauncher.util.ServiceLoaderUtils;
 import net.minecraftforge.eventbus.api.IEventBus;
 import net.minecraftforge.fml.config.IConfigEvent;
 import net.minecraftforge.fml.loading.FMLLoader;
 
+import java.util.ServiceConfigurationError;
 import java.util.ServiceLoader;
 import java.util.function.Supplier;
 
 public class Bindings {
-    private static final Bindings INSTANCE = new Bindings();
+    private Bindings() {}
 
-    private final IBindingsProvider provider;
-
-    private Bindings() {
-        final var providers = ServiceLoaderUtils.streamServiceLoader(()->ServiceLoader.load(FMLLoader.getGameLayer(), IBindingsProvider.class), sce->{}).toList();
-        if (providers.size() != 1) {
-            throw new IllegalStateException("Could not find bindings provider");
-        }
-        this.provider = providers.get(0);
-    }
+    /**
+     * The provider of the bindings
+     * @implNote May also throw a {@link ServiceConfigurationError}
+     */
+    private static final IBindingsProvider PROVIDER = ServiceLoader.load(FMLLoader.getGameLayer(), IBindingsProvider.class)
+            .findFirst().orElseThrow(() -> new IllegalStateException("Could not find bindings provider"));
 
+    /**
+     * @return A supplier of net.minecraftforge.common.MinecraftForge#EVENT_BUS
+     */
     public static Supplier<IEventBus> getForgeBus() {
-        return INSTANCE.provider.getForgeBusSupplier();
+        return PROVIDER.getForgeBusSupplier();
     }
 
     public static Supplier<I18NParser> getMessageParser() {
-        return INSTANCE.provider.getMessageParser();
+        return PROVIDER.getMessageParser();
     }
 
     public static Supplier<IConfigEvent.ConfigConfig> getConfigConfiguration() {
-        return INSTANCE.provider.getConfigConfiguration();
+        return PROVIDER.getConfigConfiguration();
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/CrashReportCallables.java

@@ -5,33 +5,93 @@
 
 package net.minecraftforge.fml;
 
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
+
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.BooleanSupplier;
 import java.util.function.Supplier;
 
-public class CrashReportCallables {
+public class CrashReportCallables
+{
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static final List<ISystemReportExtender> crashCallables = Collections.synchronizedList(new ArrayList<>());
 
+    /**
+     * Register a custom {@link ISystemReportExtender}
+     */
     public static void registerCrashCallable(ISystemReportExtender callable)
     {
         crashCallables.add(callable);
     }
 
-    public static void registerCrashCallable(String headerName, Supplier<String> reportGenerator) {
-        registerCrashCallable(new ISystemReportExtender() {
+    /**
+     * Register a {@link ISystemReportExtender system report extender} with the given header name and content
+     * generator, which will always be appended to the system report
+     * @param headerName The name of the system report entry
+     * @param reportGenerator The report generator to be called when a crash report is built
+     */
+    public static void registerCrashCallable(String headerName, Supplier<String> reportGenerator)
+    {
+        registerCrashCallable(new ISystemReportExtender()
+        {
             @Override
-            public String getLabel() {
+            public String getLabel()
+            {
                 return headerName;
             }
+
             @Override
-            public String get() {
+            public String get()
+            {
                 return reportGenerator.get();
             }
         });
     }
 
-    public static List<ISystemReportExtender> allCrashCallables() {
+    /**
+     * Register a {@link ISystemReportExtender system report extender} with the given header name and content
+     * generator, which will only be appended to the system report when the given {@link BooleanSupplier} returns true
+     * @param headerName The name of the system report entry
+     * @param reportGenerator The report generator to be called when a crash report is built
+     * @param active The supplier of the flag to be checked when a crash report is built
+     */
+    public static void registerCrashCallable(String headerName, Supplier<String> reportGenerator, BooleanSupplier active)
+    {
+        registerCrashCallable(new ISystemReportExtender()
+        {
+            @Override
+            public String getLabel()
+            {
+                return headerName;
+            }
+
+            @Override
+            public String get()
+            {
+                return reportGenerator.get();
+            }
+
+            @Override
+            public boolean isActive()
+            {
+                try
+                {
+                    return active.getAsBoolean();
+                }
+                catch (Throwable t)
+                {
+                    LOGGER.warn("CrashCallable '{}' threw an exception while checking the active flag, disabling", headerName, t);
+                    return false;
+                }
+            }
+        });
+    }
+
+    public static List<ISystemReportExtender> allCrashCallables()
+    {
         return List.copyOf(crashCallables);
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/DeferredWorkQueue.java

@@ -11,9 +11,11 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
 import java.util.concurrent.ConcurrentLinkedDeque;
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 import com.google.common.base.Stopwatch;
@@ -53,17 +55,29 @@ public class DeferredWorkQueue
     public void runTasks() {
         if (tasks.isEmpty()) return;
         LOGGER.debug(LOADING, "Dispatching synchronous work for work queue {}: {} jobs", modLoadingStage, tasks.size());
+        RuntimeException aggregate = new RuntimeException();
         Stopwatch timer = Stopwatch.createStarted();
-        tasks.forEach(t->makeRunnable(t, Runnable::run));
+        tasks.forEach(t -> makeRunnable(t, Runnable::run, aggregate));
         timer.stop();
-        LOGGER.debug(LOADING, "Synchronous work queue completed in {}", timer);
+        if (aggregate.getSuppressed().length > 0) {
+            LOGGER.fatal(
+                    LOADING,
+                    "Synchronous work queue completed exceptionally in {}, see suppressed exceptions for details:",
+                    timer,
+                    aggregate
+            );
+            //TODO 1.20: throw aggregate exception
+        } else {
+            LOGGER.debug(LOADING, "Synchronous work queue completed in {}", timer);
+        }
     }
 
-    private static void makeRunnable(TaskInfo ti, Executor executor) {
+    private static void makeRunnable(TaskInfo ti, Executor executor, RuntimeException aggregate) {
         executor.execute(() -> {
             Stopwatch timer = Stopwatch.createStarted();
             ModLoadingContext.get().setActiveContainer(ti.owner);
             try {
+                ti.future.exceptionally(t -> captureException(ti.owner.getModId(), aggregate, t));
                 ti.task.run();
             } finally {
                 ModLoadingContext.get().setActiveContainer(null);
@@ -75,13 +89,38 @@ public class DeferredWorkQueue
         });
     }
 
+    private static <T> T captureException(String modId, RuntimeException aggregate, Throwable throwable) {
+        if (throwable instanceof CompletionException ce) {
+            throwable = ce.getCause();
+        }
+        aggregate.addSuppressed(throwable);
+        LOGGER.error("Mod '{}' encountered an error in a deferred task:", modId, throwable);
+        return null;
+    }
+
     public CompletableFuture<Void> enqueueWork(final ModContainer modInfo, final Runnable work) {
-        return CompletableFuture.runAsync(work, r->tasks.add(new TaskInfo(modInfo, r)));
+        return enqueueWork(modInfo, taskInfo -> CompletableFuture.runAsync(work, r -> taskInfo.task = r));
     }
 
     public <T> CompletableFuture<T> enqueueWork(final ModContainer modInfo, final Supplier<T> work) {
-        return CompletableFuture.supplyAsync(work, r->tasks.add(new TaskInfo(modInfo, r)));
+        return enqueueWork(modInfo, taskInfo -> CompletableFuture.supplyAsync(work, r -> taskInfo.task = r));
     }
 
-    record TaskInfo(ModContainer owner, Runnable task) {}
+    private <T> CompletableFuture<T> enqueueWork(final ModContainer modInfo, Function<TaskInfo, CompletableFuture<T>> futureGen) {
+        TaskInfo taskInfo = new TaskInfo(modInfo);
+        CompletableFuture<T> future = futureGen.apply(taskInfo);
+        taskInfo.future = future;
+        tasks.add(taskInfo);
+        return future;
+    }
+
+    private static class TaskInfo {
+        private final ModContainer owner;
+        private Runnable task;
+        private CompletableFuture<?> future;
+
+        private TaskInfo(ModContainer owner) {
+            this.owner = owner;
+        }
+    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/IExtensionPoint.java

@@ -8,41 +8,111 @@ package net.minecraftforge.fml;
 import java.util.function.BiPredicate;
 import java.util.function.Supplier;
 
+/**
+ * An extension point for a mod container.
+ *
+ * <p>An extension point can be registered for a mod container using {@link ModContainer#registerExtensionPoint(Class, Supplier)}
+ * and retrieved (if present) using {@link ModContainer#getCustomExtension(Class)}. An extension point allows a mod to
+ * supply an arbitrary value as a record class to another mod or framework through their mod container class, avoiding
+ * the use of {@link InterModComms} or other external frameworks to pass around these values.</p>
+ *
+ * <p>The usual way to declare an extension point is to implement this interface on a record class, with the type
+ * parameter being a reference to the class itself. For example, {@code record MyExtension(...) extends
+ * IExtensionPoint<MyExtension>} would declare an extension point which supplies a {@code MyExtension} object. However,
+ * there is no hard requirement that an extension point's type parameter must be in reference to itself; the type
+ * parameter may reference another record class instead.</p>
+ *
+ * @param <T> the type of the record which is held by the extension point
+ */
+@SuppressWarnings("unused") // Type parameter T
 public interface IExtensionPoint<T extends Record>
 {
     /**
-     * Compatibility display test for the mod.
-     * Used for displaying compatibility with remote servers with the same mod, and on disk saves.
+     * Extension point for the compatibility display test used on the server selection screen.
      *
-     * The supplier provides my "local" version for sending across the impl or writing to disk
-     * The predicate tests the version from a remote instance or save for acceptability (Boolean is true for impl, false for local save)
-     * and returns true if the version is compatible.
+     * <em>Note: "server" and "client" refers to the {@linkplain net.minecraftforge.api.distmarker.Dist#DEDICATED_SERVER dedicated server}
+     * and {@linkplain net.minecraftforge.api.distmarker.Dist#CLIENT game client} physical distributions, rather than the
+     * {@linkplain LogicalSide logical server and client}.</em>
      *
-     * <p>Return {@code net.minecraftforge.network.NetworkConstants#IGNORESERVERONLY} in the supplier, if you wish to be ignored
-     * as a server side only mod.</p>
-     * <p>Return true in the predicate for all values of the input string (when impl boolean is true) if you are client side,
-     * and don't care about matching any potential server version.</p>
+     * <p>The {@link Supplier} provides the local compatibility version, which is sent from the server to the client
+     * for multiplayer connections or stored to disk for the world save. The {@link BiPredicate} accepts the remote
+     * compatibility version and a boolean indicating whether the remote version is from the server or a world save,
+     * where {@code true} means it is from the server and {@code false} means it is from the world save. The return
+     * value of the predicate determines whether the remote version is "compatible" for the purposes of the display test.</p>
      *
-     * <p>
-     * Examples: A server only mod
-     * </p>
+     * <p>The local compatibility version may be of the value {@link net.minecraftforge.network.NetworkConstants#IGNORESERVERONLY},
+     * in which case clients will ignore the mod's presence if it is present on the server but not on the client.
+     * However, the remote version test predicate must still accept this value as a remote version in order to display
+     * as compatible if the mod is present on the client.</p>
+     *
+     * <p><strong>The compatibility display test does not necessarily indicate the success or failure of an actual
+     * connection attempt.</strong> Factors such as display test extension misconfiguration, truncation of ping data,
+     * difference of registry data or network channels between server and client, and others may cause the result of the
+     * compatibility test to not reflect the actual likelihood of a connection successfully being established between
+     * the server and the client.</p>
+     *
+     * <p>An example declaration of a display test extension registration for a regular mod (requires to be present on
+     * server and client) is as follows:</p>
      * <pre>{@code
-     *     registerExtensionPoint(DisplayTest.class, ()->new DisplayTest(
-     *      ()->NetworkConstants.IGNORESERVERONLY, // ignore me, I'm a server only mod
-     *      (s,b)->true // i accept anything from the server or the save, if I'm asked
-     *     )
+     * String compatibilityVersion = "1"; // Could be linked with a network channel version or mod version
+     * ModLoadingContext.get().registerExtensionPoint(IExtensionPoint.DisplayTest.class,
+     *         () -> new IExtensionPoint.DisplayTest(
+     *                 () -> compatibilityVersion,
+     *                 (remoteVersion, isFromServer) -> remoteVersion.equals(compatibilityVersion)
+     *         )
+     * );
      * }</pre>
      *
-     * <p>
-     * Examples: A client only mod
-     * </p>
+     * <p>An example declaration of a display test extension registration for a <em>server-side-only</em> mod (does not
+     * require to be present on the client) is as follows:</p>
      * <pre>{@code
-     *     registerExtensionPoint(DisplayTest.class, ()->new DisplayTest(
-     *      ()->"anything. i don't care", // if i'm actually on the server, this string is sent but i'm a client only mod, so it won't be
-     *      (remoteversionstring,networkbool)->networkbool // i accept anything from the server, by returning true if it's asking about the server
-     *     )
+     * ModLoadingContext.get().registerExtensionPoint(IExtensionPoint.DisplayTest.class,
+     *         () -> new IExtensionPoint.DisplayTest(
+     *                 // Ignore this mod if not present on the client
+     *                 () -> NetworkConstants.IGNORESERVERONLY,
+     *                 // If present on the client, accept any version if from a server
+     *                 (remoteVersion, isFromServer) -> isFromServer
+     *         )
+     * );
      * }</pre>
      *
+     * <p>An example declaration of a display test extension registration for a <em>client-side-only</em> mod (does not
+     * require to be present on the server) is as follows:</p>
+     * <pre>{@code
+     * ModLoadingContext.get().registerExtensionPoint(IExtensionPoint.DisplayTest.class,
+     *         () -> new IExtensionPoint.DisplayTest(
+     *                 // Send any version from server to client, since we will be accepting any version as well
+     *                 () -> "dQw4w9WgXcQ",
+     *                 // Accept any version on the client, from server or from save
+     *                 (remoteVersion, isFromServer) -> true
+     *         )
+     * );
+     * }</pre>
+     *
+     * @see net.minecraftforge.network.ServerStatusPing
+     * @see net.minecraftforge.client.ForgeHooksClient#processForgeListPingData(net.minecraft.network.protocol.status.ServerStatus, net.minecraft.client.multiplayer.ServerData)
      */
-    record DisplayTest(Supplier<String> suppliedVersion, BiPredicate<String, Boolean> remoteVersionTest) implements IExtensionPoint<DisplayTest> {}
+    @SuppressWarnings("JavadocReference") // reference to NetworkConstants, ForgeHooksClient
+    record DisplayTest(Supplier<String> suppliedVersion, BiPredicate<String, Boolean> remoteVersionTest) implements IExtensionPoint<DisplayTest> {
+        public static final String IGNORESERVERONLY = "OHNOES\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31\uD83D\uDE31";
+
+        /**
+         * Ignores any version information coming from the server - use for server only mods
+         */
+        public static final Supplier<DisplayTest> IGNORE_SERVER_VERSION = () -> new DisplayTest(IGNORESERVERONLY, (remoteVersion, isFromServer) -> true);
+
+        /**
+         * Ignores all information and provides no information
+         */
+        public static final Supplier<DisplayTest> IGNORE_ALL_VERSION = () -> new DisplayTest("", (remoteVersion, isFromServer) -> true);
+
+        /**
+         * An optional alternative to {@link #DisplayTest(Supplier, BiPredicate)} which accepts a constant version string
+         * instead of a {@link Supplier}.
+         * <p>Internally, the provided version string is wrapped in a Supplier for you.</p>
+         */
+        public DisplayTest(String version, BiPredicate<String, Boolean> remoteVersionTest) {
+            this(() -> version, remoteVersionTest);
+        }
+    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/IModLoadingState.java

@@ -8,23 +8,79 @@ package net.minecraftforge.fml;
 import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.event.IModBusEvent;
 
-import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
+/**
+ * A mod loading state. During mod loading, the mod loader transitions between states in a defined sorted list of states,
+ * grouped into various {@link ModLoadingPhase phases}.
+ *
+ * @see IModStateProvider
+ */
 public interface IModLoadingState {
+    /**
+     * {@return the name of this state}
+     */
     String name();
+
+    /**
+     * {@return the name of the state immediately previous to this state} This may be a blank name, which indicates this
+     * is either the first mod loading state or an exceptional mod loading state (such as a situation where errors
+     * prevent the loading process from continuing normally).
+     */
     String previous();
+
+    /**
+     * {@return the mod loading phase this state belongs to} For exceptional mod loading states, this should be
+     * {@link ModLoadingPhase#ERROR}.
+     */
     ModLoadingPhase phase();
+
+    /**
+     * {@return a function returning a human-friendly message for this state}
+     */
     Function<ModList, String> message();
+
+    /**
+     * {@return an optional runnable, which runs before starting the transition from this state to the next}
+     * @see #buildTransition(Executor, Executor, Function, Function)
+     */
     Optional<Consumer<ModList>> inlineRunnable();
 
-    default <T extends Event & IModBusEvent> Optional<CompletableFuture<List<Throwable>>> buildTransition(final Executor syncExecutor, final Executor parallelExecutor) {
-        return buildTransition(syncExecutor, parallelExecutor, e->CompletableFuture.runAsync(()->{}, e), e->CompletableFuture.runAsync(()->{}, e));
+    /**
+     * Builds the transition task for this state with a blank pre-sync and post-sync task.
+     *
+     * @param syncExecutor a synchronous executor
+     * @param parallelExecutor a parallel executor
+     * @param <T> a type of event fired on the mod-specific event bus
+     * @return a transition task for this state
+     * @see #buildTransition(Executor, Executor, Function, Function)
+     */
+    default <T extends Event & IModBusEvent>
+    Optional<CompletableFuture<Void>> buildTransition(final Executor syncExecutor,
+                                                      final Executor parallelExecutor) {
+        return buildTransition(syncExecutor, parallelExecutor,
+                e -> CompletableFuture.runAsync(() -> {}, e),
+                e -> CompletableFuture.runAsync(() -> {}, e));
     }
 
-    <T extends Event & IModBusEvent> Optional<CompletableFuture<List<Throwable>>> buildTransition(Executor syncExecutor, Executor parallelExecutor, Function<Executor, CompletableFuture<Void>> preSyncTask, Function<Executor, CompletableFuture<Void>> postSyncTask);
+    /**
+     * Builds the transition task for this state. The pre-sync and post-sync task functions allow the transition builder
+     * to run these tasks on the same executor as the actual event dispatch and pre/post hooks.
+     *
+     * @param syncExecutor a synchronous executor
+     * @param parallelExecutor a parallel executor
+     * @param preSyncTask a function which returns a task to run before event pre-dispatch hook
+     * @param postSyncTask a function which returns a task to run after event post-dispatch hook
+     * @param <T> a type of event fired on the mod-specific event bus
+     * @return a transition task for this state
+     */
+    <T extends Event & IModBusEvent>
+    Optional<CompletableFuture<Void>> buildTransition(final Executor syncExecutor,
+                                                      final Executor parallelExecutor,
+                                                      final Function<Executor, CompletableFuture<Void>> preSyncTask,
+                                                      final Function<Executor, CompletableFuture<Void>> postSyncTask);
 }

fmlcore/src/main/java/net/minecraftforge/fml/IModStateProvider.java

@@ -7,6 +7,15 @@ package net.minecraftforge.fml;
 
 import java.util.List;
 
+/**
+ * Provides a list of mod loading states which the mod loader may transition between.
+ *
+ * <p>There may be multiple mod state providers in a single application, where all states from each provider is
+ * combined into a single list and ordered.</p>
+ */
 public interface IModStateProvider {
+    /**
+     * {@return the list of mod loading states known to this provider}
+     */
     List<IModLoadingState> getAllStates();
 }

fmlcore/src/main/java/net/minecraftforge/fml/IModStateTransition.java

@@ -9,7 +9,6 @@ import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.event.IModBusEvent;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
@@ -24,18 +23,26 @@ public interface IModStateTransition {
         return new NoopTransition();
     }
 
-    default <T extends Event & IModBusEvent> CompletableFuture<List<Throwable>> build(Executor syncExecutor, Executor parallelExecutor, Function<Executor, CompletableFuture<Void>> preSyncTask, Function<Executor, CompletableFuture<Void>> postSyncTask) {
-        List<CompletableFuture<List<Throwable>>> cfs = new ArrayList<>();
+    default <T extends Event & IModBusEvent>
+    CompletableFuture<Void> build(final Executor syncExecutor,
+                                  final Executor parallelExecutor,
+                                  final Function<Executor, CompletableFuture<Void>> preSyncTask,
+                                  final Function<Executor, CompletableFuture<Void>> postSyncTask) {
+        List<CompletableFuture<Void>> futures = new ArrayList<>();
+
         this.eventFunctionStream().get()
-                .map(f->(EventGenerator<T>)f)
-                .reduce((head, tail)-> addCompletableFutureTaskForModDispatch(syncExecutor, parallelExecutor, cfs, head, ModLoadingStage::currentState, tail))
-                .ifPresent(last-> addCompletableFutureTaskForModDispatch(syncExecutor, parallelExecutor, cfs, last, nextModLoadingStage(), null));
+                .map(f -> (EventGenerator<T>) f)
+                .reduce((head, tail) -> addCompletableFutureTaskForModDispatch(syncExecutor, parallelExecutor, futures, head, ModLoadingStage::currentState, tail))
+                .ifPresent(last -> addCompletableFutureTaskForModDispatch(syncExecutor, parallelExecutor, futures, last, nextModLoadingStage(), null));
+
         final CompletableFuture<Void> preSyncTaskCF = preSyncTask.apply(syncExecutor);
-        final CompletableFuture<List<Throwable>> eventDispatchCF = ModList.gather(cfs).thenCompose(ModList::completableFutureFromExceptionList);
-        final CompletableFuture<List<Throwable>> postEventDispatchCF = preSyncTaskCF.thenComposeAsync(n -> eventDispatchCF, parallelExecutor).thenApply(r -> {
-            postSyncTask.apply(syncExecutor);
-            return r;
-        });
+        final CompletableFuture<Void> eventDispatchCF = ModList.gather(futures).thenCompose(ModList::completableFutureFromExceptionList);
+        final CompletableFuture<Void> postEventDispatchCF = preSyncTaskCF
+                .thenComposeAsync(n -> eventDispatchCF, parallelExecutor)
+                .thenApply(r -> {
+                    postSyncTask.apply(syncExecutor);
+                    return null;
+                });
         return this.finalActivityGenerator().apply(syncExecutor, postEventDispatchCF);
     }
 
@@ -43,18 +50,31 @@ public interface IModStateTransition {
         return ModLoadingStage::nextState;
     }
 
-    private <T extends Event & IModBusEvent> EventGenerator<T> addCompletableFutureTaskForModDispatch(final Executor syncExecutor, final Executor parallelExecutor, final List<CompletableFuture<List<Throwable>>> completeableFutures, final EventGenerator<T> eventGenerator, BiFunction<ModLoadingStage, Throwable, ModLoadingStage> nextState, final EventGenerator<T> nextGenerator) {
-        completeableFutures.add(((BiFunction<Executor, EventGenerator<T>, CompletableFuture<List<Throwable>>>)preDispatchHook()).apply(threadSelector().apply(syncExecutor, parallelExecutor), eventGenerator));
-        completeableFutures.add(ModList.get().futureVisitor(eventGenerator, nextState).apply(threadSelector().apply(syncExecutor, parallelExecutor)));
-        completeableFutures.add(((BiFunction<Executor, EventGenerator<T>, CompletableFuture<List<Throwable>>>)postDispatchHook()).apply(threadSelector().apply(syncExecutor, parallelExecutor), eventGenerator));
+    private <T extends Event & IModBusEvent>
+    EventGenerator<T> addCompletableFutureTaskForModDispatch(final Executor syncExecutor,
+                                                             final Executor parallelExecutor,
+                                                             final List<CompletableFuture<Void>> completableFutures,
+                                                             final EventGenerator<T> eventGenerator,
+                                                             final BiFunction<ModLoadingStage, Throwable, ModLoadingStage> nextState,
+                                                             final EventGenerator<T> nextGenerator) {
+        final Executor selectedExecutor = threadSelector().apply(syncExecutor, parallelExecutor);
+
+        var preDispatchHook = (BiFunction<Executor, EventGenerator<T>, CompletableFuture<Void>>) preDispatchHook();
+        completableFutures.add(preDispatchHook.apply(selectedExecutor, eventGenerator));
+
+        completableFutures.add(ModList.get().futureVisitor(eventGenerator, nextState).apply(threadSelector().apply(syncExecutor, parallelExecutor)));
+
+        var postDispatchHook = (BiFunction<Executor, EventGenerator<T>, CompletableFuture<Void>>) postDispatchHook();
+        completableFutures.add(postDispatchHook.apply(selectedExecutor, eventGenerator));
+
         return nextGenerator;
     }
 
     Supplier<Stream<EventGenerator<?>>> eventFunctionStream();
     ThreadSelector threadSelector();
-    BiFunction<Executor, CompletableFuture<List<Throwable>>, CompletableFuture<List<Throwable>>> finalActivityGenerator();
-    BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<List<Throwable>>> preDispatchHook();
-    BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<List<Throwable>>> postDispatchHook();
+    BiFunction<Executor, CompletableFuture<Void>, CompletableFuture<Void>> finalActivityGenerator();
+    BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> preDispatchHook();
+    BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> postDispatchHook();
 
     interface EventGenerator<T extends Event & IModBusEvent> extends Function<ModContainer, T> {
         static <FN extends Event & IModBusEvent> EventGenerator<FN> fromFunction(Function<ModContainer, FN> fn) {
@@ -76,17 +96,17 @@ record NoopTransition() implements IModStateTransition {
     }
 
     @Override
-    public BiFunction<Executor, CompletableFuture<List<Throwable>>, CompletableFuture<List<Throwable>>> finalActivityGenerator() {
+    public BiFunction<Executor, CompletableFuture<Void>, CompletableFuture<Void>> finalActivityGenerator() {
         return (e, t) -> t.thenApplyAsync(Function.identity(), e);
     }
 
     @Override
-    public BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<List<Throwable>>> preDispatchHook() {
-        return (t, f)-> CompletableFuture.completedFuture(Collections.emptyList());
+    public BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> preDispatchHook() {
+        return (t, f)-> CompletableFuture.completedFuture(null);
     }
 
     @Override
-    public BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<List<Throwable>>> postDispatchHook() {
-        return (t, f)-> CompletableFuture.completedFuture(Collections.emptyList());
+    public BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> postDispatchHook() {
+        return (t, f)-> CompletableFuture.completedFuture(null);
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/ISystemReportExtender.java

@@ -10,4 +10,9 @@ import java.util.function.Supplier;
 public interface ISystemReportExtender extends Supplier<String>
 {
     String getLabel();
+
+    default boolean isActive()
+    {
+        return true;
+    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/LogicalSide.java

@@ -5,12 +5,41 @@
 
 package net.minecraftforge.fml;
 
+import net.minecraftforge.api.distmarker.Dist;
+
+/**
+ * A logical side of the Minecraft game.
+ * <p>
+ * The {@linkplain Dist#CLIENT client distribution} has a copy of the logical client and the logical server, while the
+ * {@linkplain Dist#DEDICATED_SERVER dedicated server distribution} only holds
+ * the logical server.
+ *
+ * @see Dist
+ */
 public enum LogicalSide
 {
-    CLIENT, SERVER;
+    /**
+     * The logical client of the Minecraft game, which interfaces with the player's inputs and renders the player's
+     * viewpoint.
+     * <p>
+     * The logical client is only shipped with the client distribution of the game.
+     *
+     * @see Dist#CLIENT
+     */
+    CLIENT,
+    /**
+     * The logical server of the Minecraft game, responsible for connecting to clients and running the simulation logic
+     * on the level.
+     * <p>
+     * The logical server is shipped with both client and dedicated server distributions. The client distribution runs
+     * the logical server for singleplayer mode and LAN play.
+     *
+     * @see Dist#DEDICATED_SERVER
+     */
+    SERVER;
 
     /**
-     * @return if the logical side is a server.
+     * {@return if this logical side is the server}
      */
     public boolean isServer()
     {
@@ -18,7 +47,7 @@ public enum LogicalSide
     }
 
     /**
-     * @return if the logical side is a client.
+     * {@return if the logical side is the client}
      */
     public boolean isClient()
     {

fmlcore/src/main/java/net/minecraftforge/fml/ModContainer.java

@@ -9,6 +9,7 @@ import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.config.IConfigEvent;
 import net.minecraftforge.fml.config.ModConfig;
 import net.minecraftforge.fml.event.IModBusEvent;
+import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
 import net.minecraftforge.forgespi.language.IModInfo;
 
 import java.util.EnumMap;
@@ -20,6 +21,7 @@ import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
 import java.util.function.BiFunction;
+import java.util.function.BiPredicate;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
@@ -56,9 +58,25 @@ public abstract class ModContainer
         this.namespace = this.modId;
         this.modInfo = info;
         this.modLoadingStage = ModLoadingStage.CONSTRUCT;
-        // default displaytest extension checks for version string match
-        registerExtensionPoint(IExtensionPoint.DisplayTest.class, () -> new IExtensionPoint.DisplayTest(()->this.modInfo.getVersion().toString(),
-                (incoming, isNetwork)->Objects.equals(incoming, this.modInfo.getVersion().toString())));
+
+        final String displayTestString = info.getConfig().<String>getConfigElement("displayTest")
+                .orElseGet(() -> (Boolean) info.getOwningFile().getFileProperties().getOrDefault(ModFileInfo.CLIENT_SIDE_ONLY_PROP, Boolean.FALSE) ? "IGNORE_ALL_VERSION" : "MATCH_VERSION");
+        Supplier<IExtensionPoint.DisplayTest> displayTestSupplier = switch (displayTestString) {
+            case "MATCH_VERSION" -> // default displaytest checks for version string match
+                    () -> new IExtensionPoint.DisplayTest(() -> this.modInfo.getVersion().toString(),
+                        (incoming, isNetwork) -> Objects.equals(incoming, this.modInfo.getVersion().toString()));
+            case "IGNORE_SERVER_VERSION" -> // Ignores any version information coming from the server - use for server only mods
+                    IExtensionPoint.DisplayTest.IGNORE_SERVER_VERSION;
+            case "IGNORE_ALL_VERSION" -> // Ignores all information and provides no information
+                    IExtensionPoint.DisplayTest.IGNORE_ALL_VERSION;
+            case "NONE" -> null; // NO display test at all - use this if you're going to do your own display test
+            default -> // any other value throws an exception
+                    throw new IllegalArgumentException("Invalid displayTest value supplied in mods.toml");
+        };
+        if (displayTestSupplier != null)
+            registerExtensionPoint(IExtensionPoint.DisplayTest.class, displayTestSupplier);
+        else
+            extensionPoints.remove(IExtensionPoint.DisplayTest.class);
     }
 
     /**
@@ -127,6 +145,22 @@ public abstract class ModContainer
         extensionPoints.put(point, extension);
     }
 
+    public void registerDisplayTest(IExtensionPoint.DisplayTest displayTest) {
+        registerExtensionPoint(IExtensionPoint.DisplayTest.class, () -> displayTest);
+    }
+
+    public void registerDisplayTest(Supplier<IExtensionPoint.DisplayTest> displayTest) {
+        registerExtensionPoint(IExtensionPoint.DisplayTest.class, displayTest);
+    }
+
+    public void registerDisplayTest(String version, BiPredicate<String, Boolean> remoteVersionTest) {
+        registerDisplayTest(new IExtensionPoint.DisplayTest(version, remoteVersionTest));
+    }
+
+    public void registerDisplayTest(Supplier<String> suppliedVersion, BiPredicate<String, Boolean> remoteVersionTest) {
+        registerDisplayTest(new IExtensionPoint.DisplayTest(suppliedVersion, remoteVersionTest));
+    }
+
     public void addConfig(final ModConfig modConfig) {
        configs.put(modConfig.getType(), modConfig);
     }

fmlcore/src/main/java/net/minecraftforge/fml/ModList.java

@@ -21,7 +21,7 @@ import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -54,6 +54,7 @@ public class ModList
     private List<ModContainer> mods;
     private Map<String, ModContainer> indexedMods;
     private List<ModFileScanData> modFileScanData;
+    private List<ModContainer> sortedContainers;
 
     private ModList(final List<ModFile> modFiles, final List<ModInfo> sortedList)
     {
@@ -111,7 +112,7 @@ public class ModList
         return this.fileById.get(modid);
     }
 
-    <T extends Event & IModBusEvent> Function<Executor, CompletableFuture<List<Throwable>>> futureVisitor(
+    <T extends Event & IModBusEvent> Function<Executor, CompletableFuture<Void>> futureVisitor(
             final IModStateTransition.EventGenerator<T> eventGenerator,
             final BiFunction<ModLoadingStage, Throwable, ModLoadingStage> stateChange) {
         return executor -> gather(
@@ -120,12 +121,12 @@ public class ModList
                 .collect(Collectors.toList()))
             .thenComposeAsync(ModList::completableFutureFromExceptionList, executor);
     }
-    static CompletionStage<List<Throwable>> completableFutureFromExceptionList(List<? extends Map.Entry<?, Throwable>> t) {
+    static CompletionStage<Void> completableFutureFromExceptionList(List<? extends Map.Entry<?, Throwable>> t) {
         if (t.stream().noneMatch(e->e.getValue()!=null)) {
-            return CompletableFuture.completedFuture(Collections.emptyList());
+            return CompletableFuture.completedFuture(null);
         } else {
             final List<Throwable> throwables = t.stream().filter(e -> e.getValue() != null).map(Map.Entry::getValue).collect(Collectors.toList());
-            CompletableFuture<List<Throwable>> cf = new CompletableFuture<>();
+            CompletableFuture<Void> cf = new CompletableFuture<>();
             final RuntimeException accumulator = new RuntimeException();
             cf.completeExceptionally(accumulator);
             throwables.forEach(exception -> {
@@ -156,6 +157,7 @@ public class ModList
     void setLoadedMods(final List<ModContainer> modContainers)
     {
         this.mods = modContainers;
+        this.sortedContainers = modContainers.stream().sorted(Comparator.comparingInt(c->sortedList.indexOf(c.getModInfo()))).toList();
         this.indexedMods = modContainers.stream().collect(Collectors.toMap(ModContainer::getModId, Function.identity()));
     }
 
@@ -219,6 +221,10 @@ public class ModList
         indexedMods.forEach(modContainerConsumer);
     }
 
+    public void forEachModInOrder(Consumer<ModContainer> containerConsumer) {
+        this.sortedContainers.forEach(containerConsumer);
+    }
+
     public <T> Stream<T> applyForEachModContainer(Function<ModContainer, T> function) {
         return indexedMods.values().stream().map(function);
     }

fmlcore/src/main/java/net/minecraftforge/fml/ModLoader.java

@@ -8,26 +8,25 @@ package net.minecraftforge.fml;
 import com.google.common.collect.ImmutableList;
 import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.event.IModBusEvent;
+import net.minecraftforge.fml.loading.FMLEnvironment;
 import net.minecraftforge.fml.loading.FMLLoader;
 import net.minecraftforge.fml.loading.LoadingModList;
 import net.minecraftforge.fml.loading.moddiscovery.InvalidModIdentifier;
-import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
+import net.minecraftforge.fml.loading.moddiscovery.ModInfo;
 import net.minecraftforge.fml.loading.progress.StartupMessageManager;
 import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.forgespi.language.IModLanguageProvider;
+import net.minecraftforge.forgespi.locating.ForgeFeature;
+import net.minecraftforge.forgespi.locating.IModFile;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.Executor;
+import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -83,6 +82,7 @@ public class ModLoader
     private boolean loadingStateValid;
     @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
     private final Optional<Consumer<String>> statusConsumer = StartupMessageManager.modLoaderConsumer();
+    private final Set<IModLoadingState> completedStates = new HashSet<>();
     private ModList modList;
 
     private ModLoader()
@@ -96,7 +96,7 @@ public class ModLoader
                 .map(file -> new ModLoadingWarning(null, ModLoadingStage.VALIDATE, InvalidModIdentifier.identifyJarProblem(file.getFilePath()).orElse("fml.modloading.brokenfile"), file.getFileName()))
                 .collect(Collectors.toList());
         FMLLoader.getLoadingModList().getModFiles().stream()
-                .filter(ModFileInfo::missingLicense) //Search for files with missing licenses
+                .filter(ModFileInfo::missingLicense)
                 .filter(modFileInfo -> modFileInfo.getMods().stream().noneMatch(thisModInfo -> this.loadingExceptions.stream().map(ModLoadingException::getModInfo).anyMatch(otherInfo -> otherInfo == thisModInfo))) //Ignore files where any other mod already encountered an error
                 .map(modFileInfo -> new ModLoadingException(null, ModLoadingStage.VALIDATE, "fml.modloading.missinglicense", null, modFileInfo.getFile()))
                 .forEach(this.loadingExceptions::add);
@@ -133,6 +133,7 @@ public class ModLoader
      * @param periodicTask Optional periodic task to perform on the main thread while other activities run
      */
     public void gatherAndInitializeMods(final ModWorkManager.DrivenExecutor syncExecutor, final Executor parallelExecutor, final Runnable periodicTask) {
+        ForgeFeature.registerFeature("java_version", ForgeFeature.VersionFeatureTest.forVersionString(IModInfo.DependencySide.SERVER, System.getProperty("java.version")));
         loadingStateValid = true;
         statusConsumer.ifPresent(c->c.accept("Waiting for scan to complete"));
         FMLLoader.backgroundScanHandler.waitForScanToComplete(periodicTask);
@@ -145,6 +146,22 @@ public class ModLoader
             loadingStateValid = false;
             throw new LoadingFailedException(loadingExceptions);
         }
+        statusConsumer.ifPresent(c->c.accept("Validating features"));
+        List<? extends ForgeFeature.Bound> failedBounds = loadingModList.getMods().stream()
+                .map(ModInfo::getForgeFeatures)
+                .flatMap(Collection::stream)
+                .filter(bound -> !ForgeFeature.testFeature(FMLEnvironment.dist, bound))
+                .toList();
+
+        if (!failedBounds.isEmpty()) {
+            LOGGER.fatal(CORE, "Failed to validate feature bounds for mods");
+            modList.setLoadedMods(Collections.emptyList());
+            loadingStateValid = false;
+            throw new LoadingFailedException(failedBounds.stream()
+                    .map(fb -> new ModLoadingException(fb.modInfo(), ModLoadingStage.CONSTRUCT, "fml.modloading.feature.missing", null, fb.featureName(), fb.featureBound(), ForgeFeature.featureValue(fb)))
+                    .toList());
+        }
+
         statusConsumer.ifPresent(c->c.accept("Building Mod List"));
         final List<ModContainer> modContainers = loadingModList.getModFiles().stream()
                 .map(ModFileInfo::getFile)
@@ -184,6 +201,7 @@ public class ModLoader
         statusConsumer.ifPresent(c->c.accept(state.message().apply(this.modList)));
         state.inlineRunnable().ifPresent(a->a.accept(this.modList));
         state.buildTransition(syncExecutor, parallelExecutor).ifPresent(t->waitForTransition(state, syncExecutor, ticker, t));
+        completedStates.add(state);
     }
 
     private void dispatchAndHandleError(IModLoadingState state, ModWorkManager.DrivenExecutor syncExecutor, Executor parallelExecutor, final Runnable ticker, Function<Executor, CompletableFuture<Void>> preSyncTask, Function<Executor, CompletableFuture<Void>> postSyncTask) {
@@ -194,9 +212,10 @@ public class ModLoader
         statusConsumer.ifPresent(c->c.accept(state.message().apply(this.modList)));
         state.inlineRunnable().ifPresent(a->a.accept(this.modList));
         state.buildTransition(syncExecutor, parallelExecutor, preSyncTask, postSyncTask).ifPresent(t->waitForTransition(state, syncExecutor, ticker, t));
+        completedStates.add(state);
     }
 
-    private void waitForTransition(final IModLoadingState state, final ModWorkManager.DrivenExecutor syncExecutor, final Runnable ticker, final CompletableFuture<List<Throwable>> transition) {
+    private void waitForTransition(final IModLoadingState state, final ModWorkManager.DrivenExecutor syncExecutor, final Runnable ticker, final CompletableFuture<Void> transition) {
         while (!transition.isDone()) {
             syncExecutor.drive(ticker);
         }
@@ -222,7 +241,7 @@ public class ModLoader
         }
     }
 
-    private List<ModContainer> buildMods(final ModFile modFile)
+    private List<ModContainer> buildMods(final IModFile modFile)
     {
         final Map<String, IModInfo> modInfoMap = modFile.getModFileInfo().getMods().stream().collect(Collectors.toMap(IModInfo::getModId, Function.identity()));
 
@@ -234,17 +253,29 @@ public class ModLoader
                 .filter(Objects::nonNull)
                 .collect(Collectors.toList());
         if (containers.size() != modInfoMap.size()) {
+            var modIds = modInfoMap.values().stream().map(IModInfo::getModId).sorted().collect(Collectors.toList());
+            var containerIds = containers.stream().map(c -> c != null ? c.getModId() : "(null)").sorted().collect(Collectors.toList());
+
             LOGGER.fatal(LOADING,"File {} constructed {} mods: {}, but had {} mods specified: {}",
                     modFile.getFilePath(),
-                    containers.size(), containers.stream().map(c -> c != null ? c.getModId() : "(null)").sorted().collect(Collectors.toList()),
-                    modInfoMap.size(), modInfoMap.values().stream().map(IModInfo::getModId).sorted().collect(Collectors.toList()));
+                    containers.size(), containerIds,
+                    modInfoMap.size(), modIds);
+
+            var missingClasses = new ArrayList<>(modIds);
+            missingClasses.removeAll(containerIds);
+            LOGGER.fatal(LOADING, "The following classes are missing, but are reported in the mods.toml: {}", missingClasses);
+
+            var missingMods = new ArrayList<>(containerIds);
+            missingMods.removeAll(modIds);
+            LOGGER.fatal(LOADING, "The following mods are missing, but have classes in the jar: {}", missingMods);
+
             loadingExceptions.add(new ModLoadingException(null, ModLoadingStage.CONSTRUCT, "fml.modloading.missingclasses", null, modFile.getFilePath()));
         }
         // remove errored mod containers
         return containers.stream().filter(mc -> mc.modLoadingStage != ModLoadingStage.ERROR).collect(Collectors.toList());
     }
 
-    private ModContainer buildModContainerFromTOML(final ModFile modFile, final Map<String, IModInfo> modInfoMap, final Map.Entry<String, ? extends IModLanguageProvider.IModLanguageLoader> idToProviderEntry) {
+    private ModContainer buildModContainerFromTOML(final IModFile modFile, final Map<String, IModInfo> modInfoMap, final Map.Entry<String, ? extends IModLanguageProvider.IModLanguageLoader> idToProviderEntry) {
         try {
             final String modId = idToProviderEntry.getKey();
             final IModLanguageProvider.IModLanguageLoader languageLoader = idToProviderEntry.getValue();
@@ -268,12 +299,17 @@ public class ModLoader
         return get().loadingStateValid;
     }
 
+    public boolean hasCompletedState(final String stateName) {
+        IModLoadingState state = stateManager.findState(stateName);
+        return completedStates.contains(state);
+    }
+
     public <T extends Event & IModBusEvent> void runEventGenerator(Function<ModContainer, T> generator) {
         if (!loadingStateValid) {
             LOGGER.error("Cowardly refusing to send event generator to a broken mod state");
             return;
         }
-        ModList.get().forEachModContainer((id, mc) -> mc.acceptEvent(generator.apply(mc)));
+        ModList.get().forEachModInOrder(mc -> mc.acceptEvent(generator.apply(mc)));
     }
 
     public <T extends Event & IModBusEvent> void postEvent(T e) {
@@ -281,7 +317,29 @@ public class ModLoader
             LOGGER.error("Cowardly refusing to send event {} to a broken mod state", e.getClass().getName());
             return;
         }
-        ModList.get().forEachModContainer((id, mc) -> mc.acceptEvent(e));
+        ModList.get().forEachModInOrder(mc -> mc.acceptEvent(e));
+    }
+    public <T extends Event & IModBusEvent> T postEventWithReturn(T e) {
+        if (!loadingStateValid) {
+            LOGGER.error("Cowardly refusing to send event {} to a broken mod state", e.getClass().getName());
+            return e;
+        }
+        ModList.get().forEachModInOrder(mc -> mc.acceptEvent(e));
+        return e;
+    }
+    public <T extends Event & IModBusEvent> void postEventWrapContainerInModOrder(T event) {
+        postEventWithWrapInModOrder(event, (mc, e) -> ModLoadingContext.get().setActiveContainer(mc), (mc, e) -> ModLoadingContext.get().setActiveContainer(null));
+    }
+    public <T extends Event & IModBusEvent> void postEventWithWrapInModOrder(T e, BiConsumer<ModContainer, T> pre, BiConsumer<ModContainer, T> post) {
+        if (!loadingStateValid) {
+            LOGGER.error("Cowardly refusing to send event {} to a broken mod state", e.getClass().getName());
+            return;
+        }
+        ModList.get().forEachModInOrder(mc -> {
+            pre.accept(mc, e);
+            mc.acceptEvent(e);
+            post.accept(mc, e);
+        });
     }
 
     public List<ModLoadingWarning> getWarnings()

fmlcore/src/main/java/net/minecraftforge/fml/ModLoadingContext.java

@@ -5,36 +5,57 @@
 
 package net.minecraftforge.fml;
 
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.config.IConfigSpec;
 import net.minecraftforge.fml.config.ModConfig;
+import org.slf4j.Logger;
 
+import java.util.function.BiPredicate;
 import java.util.function.Supplier;
 
 public class ModLoadingContext
 {
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static final ThreadLocal<ModLoadingContext> context = ThreadLocal.withInitial(ModLoadingContext::new);
+    private ModContainer activeContainer;
     private Object languageExtension;
     private ModLoadingStage stage;
 
+    /**
+     * @deprecated Use the context provided by your language loader in your mod's constructor.
+     */
+    @Deprecated(forRemoval = true, since = "1.21.1")
     public static ModLoadingContext get() {
         return context.get();
     }
 
-    private ModContainer activeContainer;
-
+    /**
+     * @deprecated Going to be moved to ForgeHooks for internal use.
+     */
+    @Deprecated(forRemoval = true, since = "1.21.1")
     public void setActiveContainer(final ModContainer container) {
         this.activeContainer = container;
         this.languageExtension = container == null ? null : container.contextExtension.get();
     }
 
+    /**
+     * Going to be moved to ForgeHooks for internal use.
+     * @deprecated Override/Use {@link ModLoadingContext#getContainer()}
+     */
+    @Deprecated(forRemoval = true, since = "1.21.1")
     public ModContainer getActiveContainer() {
         return activeContainer == null ? ModList.get().getModContainerById("minecraft").orElseThrow(()->new RuntimeException("Where is minecraft???!")) : activeContainer;
     }
 
+    @Deprecated(forRemoval = true, since = "1.21.1")
     public String getActiveNamespace() {
         return activeContainer == null ? "minecraft" : activeContainer.getNamespace();
     }
 
+    public ModContainer getContainer() {
+        return getActiveContainer();
+    }
+
     /**
      * Register an {@link IExtensionPoint} with the mod container.
      * @param point The extension point to register
@@ -42,15 +63,67 @@ public class ModLoadingContext
      * @param <T> The type signature of the extension operator
      */
     public <T extends Record & IExtensionPoint<T>> void registerExtensionPoint(Class<? extends IExtensionPoint<T>> point, Supplier<T> extension) {
-        getActiveContainer().registerExtensionPoint(point, extension);
+        getContainer().registerExtensionPoint(point, extension);
+    }
+
+    /**
+     * Register a {@link IExtensionPoint.DisplayTest} with the mod container.
+     * <p>A shorthand for registering a DisplayTest with {@link #registerExtensionPoint(Class, Supplier)}.</p>
+     * @param displayTest The {@link IExtensionPoint.DisplayTest} to register
+     */
+    public void registerDisplayTest(IExtensionPoint.DisplayTest displayTest) {
+        getContainer().registerDisplayTest(() -> displayTest);
+    }
+
+    /**
+     * Register a {@link IExtensionPoint.DisplayTest} with the mod container.
+     * <p>A shorthand for registering a DisplayTest supplier with {@link #registerExtensionPoint(Class, Supplier)}.</p>
+     * @param displayTest The {@link Supplier<IExtensionPoint.DisplayTest>} to register
+     */
+    public void registerDisplayTest(Supplier<IExtensionPoint.DisplayTest> displayTest) {
+        getContainer().registerDisplayTest(displayTest);
+    }
+
+    /**
+     * Register a {@link IExtensionPoint.DisplayTest} with the mod container.
+     * <p>A shorthand for registering a DisplayTest with {@link #registerExtensionPoint(Class, Supplier)} that also
+     * creates the DisplayTest instance for you using the provided parameters.</p>
+     * @see IExtensionPoint.DisplayTest#DisplayTest(String, BiPredicate)
+     */
+    public void registerDisplayTest(String version, BiPredicate<String, Boolean> remoteVersionTest) {
+        getContainer().registerDisplayTest(new IExtensionPoint.DisplayTest(version, remoteVersionTest));
+    }
+
+    /**
+     * Register a {@link IExtensionPoint.DisplayTest} with the mod container.
+     * <p>A shorthand for registering a DisplayTest with {@link #registerExtensionPoint(Class, Supplier)} that also
+     * creates the DisplayTest instance for you using the provided parameters.</p>
+     * @see IExtensionPoint.DisplayTest#DisplayTest(Supplier, BiPredicate)
+     */
+    public void registerDisplayTest(Supplier<String> suppliedVersion, BiPredicate<String, Boolean> remoteVersionTest) {
+        getContainer().registerDisplayTest(new IExtensionPoint.DisplayTest(suppliedVersion, remoteVersionTest));
     }
 
     public void registerConfig(ModConfig.Type type, IConfigSpec<?> spec) {
-        getActiveContainer().addConfig(new ModConfig(type, spec, getActiveContainer()));
+        if (spec.isEmpty())
+        {
+            // This handles the case where a mod tries to register a config, without any options configured inside it.
+            LOGGER.debug("Attempted to register an empty config for type {} on mod {}", type, getContainer().getModId());
+            return;
+        }
+
+        getContainer().addConfig(new ModConfig(type, spec, getContainer()));
     }
 
     public void registerConfig(ModConfig.Type type, IConfigSpec<?> spec, String fileName) {
-        getActiveContainer().addConfig(new ModConfig(type, spec, getActiveContainer(), fileName));
+        if (spec.isEmpty())
+        {
+            // This handles the case where a mod tries to register a config, without any options configured inside it.
+            LOGGER.debug("Attempted to register an empty config for type {} on mod {} using file name {}", type, getContainer().getModId(), fileName);
+            return;
+        }
+
+        getContainer().addConfig(new ModConfig(type, spec, getContainer(), fileName));
     }
 
 

fmlcore/src/main/java/net/minecraftforge/fml/ModLoadingPhase.java

@@ -5,10 +5,34 @@
 
 package net.minecraftforge.fml;
 
+/**
+ * Phases of mod loading, for grouping mod loading states.
+ */
 public enum ModLoadingPhase {
+    /**
+     * Special phase for exceptional situations and error handling, where mod loading cannot continue normally.
+     *
+     * <p>There is conventionally only one state with this phase.</p>
+     */
     ERROR, // Special state for error handling
+    /**
+     * Phase for discovering and gathering mods for loading.
+     */
     GATHER,
+    /**
+     * Phase for the loading of mods found from mod discovery.
+     *
+     * @see #GATHER
+     */
     LOAD,
+    /**
+     * Phase after mod loading has completed, for post-loading tasks.
+     *
+     * @see #LOAD
+     */
     COMPLETE,
-    DONE;
+    /**
+     * Marker phase for the last state in the full mod loading process.
+     */
+    DONE
 }

fmlcore/src/main/java/net/minecraftforge/fml/ModLoadingStage.java

@@ -5,16 +5,53 @@
 
 package net.minecraftforge.fml;
 
+/**
+ * Mod loading stage of mod containers during the mod loading process. These will have a corresponding {@link ModLoadingState}
+ * in the basic mod loading process provided by FML.
+ *
+ * <p>Each mod loading stage has a global {@link DeferredWorkQueue}, which is populated during the execution of the state
+ * associated with this stage and emptied at the end of the state's execution.</p>
+ */
 public enum ModLoadingStage
 {
+    /**
+     * Special stage for exceptional situations and error handling.
+     */
     ERROR,
+    /**
+     * Validation of the mod list.
+     * TODO: figure out where this is used and why this exists instead of CONSTRUCT being the first normal stage
+     */
     VALIDATE,
+    /**
+     * Default stage of mod containers after construction.
+     */
     CONSTRUCT,
+    /**
+     * Common (non-side-specific) setup and initialization.
+     */
     COMMON_SETUP,
+    /**
+     * Side-specific setup and initialization.
+     *
+     * @see net.minecraftforge.api.distmarker.Dist
+     */
     SIDED_SETUP,
+    /**
+     * Stage for enqueuing {@link net.minecraftforge.fml.InterModComms} messages for later processing.
+     */
     ENQUEUE_IMC,
+    /**
+     * Stage for processing received messages though {@link net.minecraftforge.fml.InterModComms}.
+     */
     PROCESS_IMC,
+    /**
+     * Marks the completion of mod loading for this container.
+     */
     COMPLETE,
+    /**
+     * Marks the completion of the full mod loading process.
+     */
     DONE;
 
     private final DeferredWorkQueue deferredWorkQueue;
@@ -23,14 +60,27 @@ public enum ModLoadingStage
         deferredWorkQueue = new DeferredWorkQueue(this);
     }
 
+    /**
+     * {@return the next stage after this stage, or {@link #ERROR} if the exception is not {@code null}}
+     *
+     * @param exception the exception that occurred during this stage, may be {@code null}
+     */
     ModLoadingStage nextState(Throwable exception) {
         return exception != null ? ERROR : values()[this.ordinal()+1];
     }
 
+    /**
+     * {@return this stage, or {@link #ERROR} if the exception is not {@code null}}
+     *
+     * @param exception the exception that occurred during this stage, may be {@code null}
+     */
     public ModLoadingStage currentState(Throwable exception) {
         return exception != null ? ERROR : this;
     }
 
+    /**
+     * {@return the deferred work queue for this stage}
+     */
     public DeferredWorkQueue getDeferredWorkQueue() {
         return deferredWorkQueue;
     }

fmlcore/src/main/java/net/minecraftforge/fml/ModLoadingState.java

@@ -8,31 +8,91 @@ package net.minecraftforge.fml;
 import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.event.IModBusEvent;
 
-import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
-public record ModLoadingState(String name, String previous, Function<ModList, String> message, ModLoadingPhase phase, Optional<Consumer<ModList>> inlineRunnable, Optional<IModStateTransition> transition) implements IModLoadingState {
+/**
+ * Implementation of the {@link IModLoadingState} interface.
+ *
+ * @param name           the name of this state
+ * @param previous       the name of the state immediately previous to this state
+ * @param message        a function returning a human-friendly message for this state
+ * @param phase          the mod loading phase this state belongs to
+ * @param inlineRunnable an optional runnable, which runs before starting the transition from this state to the next
+ * @param transition     optional state transition information
+ */
+public record ModLoadingState(String name, String previous,
+                              Function<ModList, String> message,
+                              ModLoadingPhase phase,
+                              Optional<Consumer<ModList>> inlineRunnable,
+                              Optional<IModStateTransition> transition) implements IModLoadingState {
     @Override
-    public <T extends Event & IModBusEvent> Optional<CompletableFuture<List<Throwable>>> buildTransition(final Executor syncExecutor, final Executor parallelExecutor, Function<Executor, CompletableFuture<Void>> preSyncTask, Function<Executor, CompletableFuture<Void>> postSyncTask) {
-        return transition.map(t->t.build(syncExecutor, parallelExecutor, preSyncTask, postSyncTask));
+    public <T extends Event & IModBusEvent>
+    Optional<CompletableFuture<Void>> buildTransition(final Executor syncExecutor,
+                                                      final Executor parallelExecutor,
+                                                      final Function<Executor, CompletableFuture<Void>> preSyncTask,
+                                                      final Function<Executor, CompletableFuture<Void>> postSyncTask) {
+        return transition.map(t -> t.build(syncExecutor, parallelExecutor, preSyncTask, postSyncTask));
     }
 
+    /**
+     * {@return an empty mod loading state} The mod loading state has a blank human-readable message, no inline runnable,
+     * and no state transition information.
+     *
+     * @param name     the name of the state
+     * @param previous the name of the immediately previous state to this state
+     * @param phase    the mod loading phase the state belongs to
+     */
     public static ModLoadingState empty(final String name, final String previous, final ModLoadingPhase phase) {
-        return new ModLoadingState(name, previous, ml->"", phase, Optional.empty(), Optional.empty());
+        return new ModLoadingState(name, previous, ml -> "", phase, Optional.empty(), Optional.empty());
     }
 
-    public static ModLoadingState withTransition(final String name, final String previous, final ModLoadingPhase phase, IModStateTransition transition) {
-        return new ModLoadingState(name, previous, ml->"Processing transition "+name, phase, Optional.empty(), Optional.of(transition));
+    /**
+     * Returns a mod loading state with state transition information and a default human-friendly message of
+     * {@code Processing transition [name]}.
+     *
+     * @param name       the name of the state
+     * @param previous   the name of the immediately previous state to this state
+     * @param phase      the mod loading phase the state belongs to
+     * @param transition the state transition information
+     * @return a mod loading state with state transition information and a default message
+     */
+    public static ModLoadingState withTransition(final String name, final String previous, final ModLoadingPhase phase,
+                                                 final IModStateTransition transition) {
+        return new ModLoadingState(name, previous, ml -> "Processing transition " + name, phase, Optional.empty(), Optional.of(transition));
     }
 
-    public static ModLoadingState withTransition(final String name, final String previous, final Function<ModList, String> message, final ModLoadingPhase phase, IModStateTransition transition) {
+    /**
+     * Returns a mod loading state with state transition information and a custom human-friendly message function.
+     *
+     * @param name       the name of the state
+     * @param previous   the name of the immediately previous state to this state
+     * @param message    a function returning a human-friendly message for this state
+     * @param phase      the mod loading phase the state belongs to
+     * @param transition the state transition information
+     * @return a mod loading state with state transition information and a custom message
+     */
+    public static ModLoadingState withTransition(final String name, final String previous,
+                                                 final Function<ModList, String> message, final ModLoadingPhase phase,
+                                                 final IModStateTransition transition) {
         return new ModLoadingState(name, previous, message, phase, Optional.empty(), Optional.of(transition));
     }
-    public static ModLoadingState withInline(final String name, final String previous, final ModLoadingPhase phase, Consumer<ModList> inline) {
-        return new ModLoadingState(name, previous, ml->"Processing work "+name, phase, Optional.of(inline), Optional.empty());
+
+    /**
+     * Returns a mod loading state with an inline runnable and a default human-friendly message of {@code Processing
+     * work [name]}.
+     *
+     * @param name     the name of the state
+     * @param previous the name of the immediately previous state to this state
+     * @param phase    the mod loading phase the state belongs to
+     * @param inline   an optional runnable, which runs before starting the transition from this state to the next
+     * @return a mod loading state with an inline runnable and default message
+     */
+    public static ModLoadingState withInline(final String name, final String previous, final ModLoadingPhase phase,
+                                             final Consumer<ModList> inline) {
+        return new ModLoadingState(name, previous, ml -> "Processing work " + name, phase, Optional.of(inline), Optional.empty());
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/ModStateManager.java

@@ -39,4 +39,13 @@ public class ModStateManager {
         nodes.forEach(n->graph.putEdge(lookup.getOrDefault(n.previous(), dummy), n));
         return TopologicalSort.topologicalSort(graph, Comparator.comparingInt(nodes::indexOf)).stream().filter(st->st!=dummy).toList();
     }
+
+    public IModLoadingState findState(final String stateName) {
+        return stateMap.values()
+                .stream()
+                .flatMap(Collection::stream)
+                .filter(mls -> mls.name().equals(stateName))
+                .findFirst()
+                .orElseThrow(() -> new IllegalArgumentException("Unknown IModLoadingState: " + stateName));
+    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/VersionChecker.java

@@ -51,8 +51,8 @@ public class VersionChecker
         BETA(),
         BETA_OUTDATED(6, true);
 
-        final int sheetOffset;
-        final boolean draw, animated;
+        private final int sheetOffset;
+        private final boolean draw, animated;
 
         Status()
         {
@@ -91,6 +91,9 @@ public class VersionChecker
             return animated;
         }
 
+        public boolean isOutdated() {
+            return this == OUTDATED || this == BETA_OUTDATED;
+        }
     }
 
     public record CheckResult(VersionChecker.Status status, ComparableVersion target, Map<ComparableVersion, String> changes, String url) {}
@@ -117,14 +120,22 @@ public class VersionChecker
             /**
              * Returns the response body as a String for the given URL while following redirects
              */
-            private String openUrlString(URL url) throws IOException, URISyntaxException, InterruptedException {
+            private String openUrlString(URL url, IModInfo mod) throws IOException, URISyntaxException, InterruptedException {
                 URL currentUrl = url;
+
+                final StringBuilder sb = new StringBuilder();
+                sb.append("Java-http-client/").append(System.getProperty("java.version")).append(' ');
+                sb.append("MinecraftForge/").append(FMLLoader.versionInfo().mcAndForgeVersion()).append(' ');
+                sb.append(mod.getModId()).append('/').append(mod.getVersion());
+                final String userAgent = sb.toString();
+
                 for (int redirects = 0; redirects < MAX_HTTP_REDIRECTS; redirects++)
                 {
                     var request = HttpRequest.newBuilder()
                             .uri(currentUrl.toURI())
                             .timeout(Duration.ofSeconds(HTTP_TIMEOUT_SECS))
                             .setHeader("Accept-Encoding", "gzip")
+                            .setHeader("User-Agent", userAgent)
                             .GET()
                             .build();
 
@@ -166,7 +177,7 @@ public class VersionChecker
                     URL url = mod.getUpdateURL().get();
                     LOGGER.info("[{}] Starting version check at {}", mod.getModId(), url.toString());
 
-                    String data = openUrlString(url);
+                    String data = openUrlString(url, mod);
 
                     LOGGER.debug("[{}] Received version check data:\n{}", mod.getModId(), data);
 
@@ -249,7 +260,7 @@ public class VersionChecker
                     LOGGER.warn("Failed to process update information", e);
                     status = FAILED;
                 }
-                results.put(mod, new CheckResult(status, target, changes, display_url));
+                RESULTS.put(mod, new CheckResult(status, target, changes, display_url));
             }
         }.start();
     }
@@ -265,12 +276,12 @@ public class VersionChecker
         return ret;
     }
 
-    private static Map<IModInfo, CheckResult> results = new ConcurrentHashMap<>();
+    private static final Map<IModInfo, CheckResult> RESULTS = new ConcurrentHashMap<>();
     private static final CheckResult PENDING_CHECK = new CheckResult(PENDING, null, null, null);
 
     public static CheckResult getResult(IModInfo mod)
     {
-        return results.getOrDefault(mod, PENDING_CHECK);
+        return RESULTS.getOrDefault(mod, PENDING_CHECK);
     }
 
 }

fmlcore/src/main/java/net/minecraftforge/fml/config/ConfigFileTypeHandler.java

@@ -10,11 +10,11 @@ import com.electronwill.nightconfig.core.file.CommentedFileConfig;
 import com.electronwill.nightconfig.core.file.FileWatcher;
 import com.electronwill.nightconfig.core.io.ParsingException;
 import com.electronwill.nightconfig.core.io.WritingMode;
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.FMLConfig;
 import net.minecraftforge.fml.loading.FMLPaths;
 import org.apache.commons.io.FilenameUtils;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -24,7 +24,7 @@ import java.util.function.Function;
 import static net.minecraftforge.fml.config.ConfigTracker.CONFIG;
 
 public class ConfigFileTypeHandler {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     static ConfigFileTypeHandler TOML = new ConfigFileTypeHandler();
     private static final Path defaultConfigPath = FMLPaths.GAMEDIR.get().resolve(FMLConfig.defaultConfigPath());
 

fmlcore/src/main/java/net/minecraftforge/fml/config/ConfigTracker.java

@@ -7,18 +7,18 @@ package net.minecraftforge.fml.config;
 
 import com.electronwill.nightconfig.core.CommentedConfig;
 import com.electronwill.nightconfig.core.file.CommentedFileConfig;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-import org.apache.logging.log4j.Marker;
-import org.apache.logging.log4j.MarkerManager;
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
+import org.slf4j.Marker;
+import org.slf4j.MarkerFactory;
 
 import java.nio.file.Path;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 
 public class ConfigTracker {
-    private static final Logger LOGGER = LogManager.getLogger();
-    static final Marker CONFIG = MarkerManager.getMarker("CONFIG");
+    private static final Logger LOGGER = LogUtils.getLogger();
+    static final Marker CONFIG = MarkerFactory.getMarker("CONFIG");
     public static final ConfigTracker INSTANCE = new ConfigTracker();
     private final ConcurrentHashMap<String, ModConfig> fileMap;
     private final EnumMap<ModConfig.Type, Set<ModConfig>> configSets;
@@ -66,8 +66,12 @@ public class ConfigTracker {
     private void closeConfig(final ModConfig config, final Path configBasePath) {
         if (config.getConfigData() != null) {
             LOGGER.trace(CONFIG, "Closing config file type {} at {} for {}", config.getType(), config.getFileName(), config.getModId());
-            config.save();
+            // stop the filewatcher before we save the file and close it, so reload doesn't fire
             config.getHandler().unload(configBasePath, config);
+            var unloading = IConfigEvent.unloading(config);
+            if (unloading != null)
+                config.fireEvent(unloading);
+            config.save();
             config.setConfigData(null);
         }
     }

fmlcore/src/main/java/net/minecraftforge/fml/config/IConfigEvent.java

@@ -10,8 +10,11 @@ import net.minecraftforge.fml.Bindings;
 
 import java.util.function.Function;
 
+import org.jetbrains.annotations.Nullable;
+
 public interface IConfigEvent {
-    record ConfigConfig(Function<ModConfig, IConfigEvent> loading, Function<ModConfig, IConfigEvent> reloading) {}
+    record ConfigConfig(Function<ModConfig, IConfigEvent> loading, Function<ModConfig, IConfigEvent> reloading, @Nullable Function<ModConfig, IConfigEvent> unloading) {}
+
     ConfigConfig CONFIGCONFIG = Bindings.getConfigConfiguration().get();
 
     static IConfigEvent reloading(ModConfig modConfig) {
@@ -20,6 +23,9 @@ public interface IConfigEvent {
     static IConfigEvent loading(ModConfig modConfig) {
         return CONFIGCONFIG.loading().apply(modConfig);
     }
+    @Nullable static IConfigEvent unloading(ModConfig modConfig) {
+        return CONFIGCONFIG.unloading() == null ? null : CONFIGCONFIG.unloading().apply(modConfig);
+    }
     ModConfig getConfig();
 
     @SuppressWarnings("unchecked")

fmlloader/build.gradle

@@ -11,29 +11,36 @@ dependencyUpdates.rejectVersionIf { isNonStable(it.candidate.version) }
 configurations.forEach{ it.transitive = false }
 
 dependencies {
-    implementation('net.sf.jopt-simple:jopt-simple:5.0.4')
-    compileOnly('org.jetbrains:annotations:23.0.0')
+    compileOnly("org.jetbrains:annotations:${JETBRAINS_ANNOTATIONS_VERSION}")
+
     api("org.ow2.asm:asm:${ASM_VERSION}")
     api("org.ow2.asm:asm-tree:${ASM_VERSION}")
     api("org.ow2.asm:asm-commons:${ASM_VERSION}")
-    api('net.minecraftforge:forgespi:4.0.+')
-    api('org.apache.logging.log4j:log4j-api:2.17.0')
-    api('org.slf4j:slf4j-api:1.8.0-beta4')
-    api('com.google.guava:guava:21.0')
-    api('com.google.code.gson:gson:2.8.9')
-    api('org.apache.maven:maven-artifact:3.8.1')
-    api('org.apache.commons:commons-lang3:3.12.0')
-    api('com.electronwill.night-config:core:3.6.4')
-    api('com.electronwill.night-config:toml:3.6.4')
-    api('cpw.mods:modlauncher:9.0.+')
-    api('net.minecraftforge:coremods:5.0.+')
+    api("net.minecraftforge:forgespi:${SPI_VERSION}")
+    api("org.apache.logging.log4j:log4j-api:${LOG4J_VERSION}")
+    api("org.slf4j:slf4j-api:${SLF4J_API_VERSION}")
+    api("com.google.guava:guava:${GUAVA_VERSION}")
+    api("com.google.code.gson:gson:${GSON_VERSION}")
+    api("org.apache.maven:maven-artifact:${APACHE_MAVEN_ARTIFACT_VERSION}")
+    api("org.apache.commons:commons-lang3:${APACHE_COMMONS_LANG3_VERSION}")
+    api("com.electronwill.night-config:core:${NIGHTCONFIG_VERSION}")
+    api("com.electronwill.night-config:toml:${NIGHTCONFIG_VERSION}")
+    api("cpw.mods:modlauncher:${MODLAUNCHER_VERSION}")
+    api("net.minecraftforge:coremods:${COREMODS_VERSION}")
+    api("com.mojang:logging:${MOJANG_LOGGING_VERSION}")
+    api "net.minecraftforge:JarJarSelector:${JARJAR_VERSION}"
+    api "net.minecraftforge:JarJarMetadata:${JARJAR_VERSION}"
+
+    implementation("net.sf.jopt-simple:jopt-simple:${JOPT_SIMPLE_VERSION}")
     implementation("cpw.mods:securejarhandler:${SECUREJARHANDLER_VERSION}")
-    implementation('org.apache.logging.log4j:log4j-core:2.17.0')
-    annotationProcessor('org.apache.logging.log4j:log4j-core:2.17.0')
-    implementation('net.minecraftforge:accesstransformers:8.0.4')
-    implementation('net.minecrell:terminalconsoleappender:1.2.0')
-//    implementation('org.jline:jline:3.12.+')
-    testCompileOnly('org.jetbrains:annotations:21.0.0')
+    implementation("net.minecraftforge:accesstransformers:${ACCESSTRANSFORMERS_VERSION}")
+    implementation("net.minecrell:terminalconsoleappender:${TERMINALCONSOLEAPPENDER_VERSION}")
+    // implementation("org.jline:jline:${JLINE_VERSION}")
+
+    implementation("org.apache.logging.log4j:log4j-core:${LOG4J_VERSION}")
+    annotationProcessor("org.apache.logging.log4j:log4j-core:${LOG4J_VERSION}")
+
+    testCompileOnly("org.jetbrains:annotations:${JETBRAINS_ANNOTATIONS_VERSION}")
     testRuntimeOnly("cpw.mods:bootstraplauncher:${BOOTSTRAPLAUNCHER_VERSION}")
 }
 

fmlloader/src/main/java/net/minecraftforge/fml/common/asm/ObjectHolderDefinalize.java

@@ -7,7 +7,12 @@ package net.minecraftforge.fml.common.asm;
 
 import java.util.EnumSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.Type;
@@ -20,26 +25,56 @@ import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
  * Will also de-finalize all fields in on class level annotations.
  */
 public class ObjectHolderDefinalize implements ILaunchPluginService {
-
-    private final String OBJECT_HOLDER = "Lnet/minecraftforge/registries/ObjectHolder;"; //Don't directly reference this to prevent class loading.
+    // Hardcoded map of vanilla classes that should have object holders for each field of the given registry type.
+    // IMPORTANT: Updates to this collection must be reflected in ObjectHolderRegistry. Duplicated cuz classloaders, yay!
+    // Classnames are validated in ObjectHolderRegistry.
+    private static final Map<String, VanillaObjectHolderData> VANILLA_OBJECT_HOLDERS = Stream.of(
+            new VanillaObjectHolderData("net.minecraft.world.level.block.Blocks", "block", "net.minecraft.world.level.block.Block"),
+            new VanillaObjectHolderData("net.minecraft.world.item.Items", "item", "net.minecraft.world.item.Item"),
+            new VanillaObjectHolderData("net.minecraft.world.item.enchantment.Enchantments", "enchantment", "net.minecraft.world.item.enchantment.Enchantment"),
+            new VanillaObjectHolderData("net.minecraft.world.effect.MobEffects", "mob_effect", "net.minecraft.world.effect.MobEffect"),
+            new VanillaObjectHolderData("net.minecraft.core.particles.ParticleTypes", "particle_type", "net.minecraft.core.particles.ParticleType"),
+            new VanillaObjectHolderData("net.minecraft.sounds.SoundEvents", "sound_event", "net.minecraft.sounds.SoundEvent")
+    ).collect(Collectors.toMap(VanillaObjectHolderData::holderClass, Function.identity()));
+    private static final Set<String> VANILLA_OBJECT_HOLDER_CLASSES = VANILLA_OBJECT_HOLDERS.keySet().stream()
+            .map(it -> it.replace('.', '/'))
+            .collect(Collectors.toUnmodifiableSet());
+    private static final String OBJECT_HOLDER = "Lnet/minecraftforge/registries/ObjectHolder;"; //Don't directly reference this to prevent class loading.
+    private static final int PUBLIC_STATIC_FINAL_FLAGS = Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL;
 
     @Override
     public String name() {
         return "object_holder_definalize";
     }
 
-
     private static final EnumSet<Phase> YAY = EnumSet.of(Phase.AFTER);
     private static final EnumSet<Phase> NAY = EnumSet.noneOf(Phase.class);
 
     @Override
-    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty)
-    {
-        return isEmpty ? NAY : YAY;
+    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty) {
+        if (isEmpty)
+            return NAY;
+
+        // Let's skip processing classes that definitely don't have object holders
+        String internalName = classType.getInternalName();
+
+        // Forge classes that aren't in the debug package (that package is used for tests)
+        if (internalName.startsWith("net/minecraftforge/") && !internalName.substring(18).contains("debug")
+            && !internalName.equals("net/minecraftforge/common/crafting/ConditionalRecipe"))
+            return NAY;
+
+        // Vanilla classes that don't have object holders
+        if (internalName.startsWith("com/mojang/"))
+            return NAY;
+
+        // ...except specific ones we added to the VANILLA_OBJECT_HOLDERS map
+        if (internalName.startsWith("net/minecraft/") && !VANILLA_OBJECT_HOLDER_CLASSES.contains(internalName))
+            return NAY;
+
+        return YAY;
     }
 
-    private boolean hasHolder(List<AnnotationNode> lst)
-    {
+    private boolean hasHolder(List<AnnotationNode> lst) {
         return lst != null && lst.stream().anyMatch(n -> n.desc.equals(OBJECT_HOLDER));
     }
 
@@ -62,10 +97,9 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
     {
         final AtomicBoolean changes = new AtomicBoolean();
         //Must be public static finals, and non-array objects
-        final int flags = Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL;
 
         //Fix Annotated Fields before injecting from class level
-        classNode.fields.stream().filter(f -> ((f.access & flags) == flags) && f.desc.startsWith("L") && hasHolder(f.visibleAnnotations)).forEach(f ->
+        classNode.fields.stream().filter(f -> ((f.access & PUBLIC_STATIC_FINAL_FLAGS) == PUBLIC_STATIC_FINAL_FLAGS) && f.desc.startsWith("L") && hasHolder(f.visibleAnnotations)).forEach(f ->
         {
             int prev = f.access;
             f.access &= ~Opcodes.ACC_FINAL; //Strip final
@@ -73,11 +107,9 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
             changes.compareAndSet(false, prev != f.access);
         });
 
-        if (hasHolder(classNode.visibleAnnotations)) //Class level, de-finalize all fields and add @ObjectHolder to them!
+        if (VANILLA_OBJECT_HOLDERS.containsKey(classType.getClassName())) //Class level, de-finalize all fields and add @ObjectHolder to them!
         {
-            @SuppressWarnings("unused")
-            String value = getValue(classNode.visibleAnnotations);
-            classNode.fields.stream().filter(f -> ((f.access & flags) == flags) && f.desc.startsWith("L")).forEach(f ->
+            classNode.fields.stream().filter(f -> ((f.access & PUBLIC_STATIC_FINAL_FLAGS) == PUBLIC_STATIC_FINAL_FLAGS) && f.desc.startsWith("L")).forEach(f ->
             {
                 int prev = f.access;
                 f.access &= ~Opcodes.ACC_FINAL;
@@ -95,4 +127,5 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
         return changes.get() ? ComputeFlags.SIMPLE_REWRITE : ComputeFlags.NO_REWRITE;
     }
 
+    private record VanillaObjectHolderData(String holderClass, String registryName, String registryType) {}
 }

fmlloader/src/main/java/net/minecraftforge/fml/common/asm/RuntimeEnumExtender.java

@@ -9,9 +9,7 @@ import java.util.EnumSet;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import net.minecraftforge.fml.loading.AdvancedLogMessageAdapter;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import com.mojang.logging.LogUtils;
 import org.objectweb.asm.Label;
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.Type;
@@ -21,6 +19,9 @@ import org.objectweb.asm.tree.FieldNode;
 import org.objectweb.asm.tree.MethodNode;
 
 import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
+import org.slf4j.Logger;
+import org.slf4j.Marker;
+import org.slf4j.MarkerFactory;
 
 /**
  * Modifies specified enums to allow runtime extension by making the $VALUES field non-final and
@@ -28,7 +29,7 @@ import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
  */
 public class RuntimeEnumExtender implements ILaunchPluginService {
 
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private final Type STRING = Type.getType(String.class);
     private final Type ENUM = Type.getType(Enum.class);
     private final Type MARKER_IFACE = Type.getType("Lnet/minecraftforge/common/IExtensibleEnum;");
@@ -63,43 +64,49 @@ public class RuntimeEnumExtender implements ILaunchPluginService {
         final int flags = Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL | Opcodes.ACC_SYNTHETIC;
 
         FieldNode values = classNode.fields.stream().filter(f -> f.desc.contentEquals(array.getDescriptor()) && ((f.access & flags) == flags)).findFirst().orElse(null);
-        
+
         if (!classNode.interfaces.contains(MARKER_IFACE.getInternalName())) {
             return ComputeFlags.NO_REWRITE;
         }
-        
+
         //Static methods named "create" with first argument as a string
         List<MethodNode> candidates = classNode.methods.stream()
                 .filter(m -> ((m.access & Opcodes.ACC_STATIC) != 0) && m.name.equals("create"))
                 .collect(Collectors.toList());
-        
+
         if (candidates.isEmpty()) {
             throw new IllegalStateException("IExtensibleEnum has no candidate factory methods: " + classType.getClassName());
         }
-        
+
         candidates.forEach(mtd ->
         {
             Type[] args = Type.getArgumentTypes(mtd.desc);
             if (args.length == 0 || !args[0].equals(STRING)) {
-                LOGGER.fatal(()->new AdvancedLogMessageAdapter(sb-> {
+                if (LOGGER.isErrorEnabled(LogUtils.FATAL_MARKER))
+                {
+                    StringBuilder sb = new StringBuilder();
                     sb.append("Enum has create method without String as first parameter:\n");
                     sb.append("  Enum: ").append(classType.getDescriptor()).append("\n");
                     sb.append("  Target: ").append(mtd.name).append(mtd.desc).append("\n");
-                }));
+                    LOGGER.error(LogUtils.FATAL_MARKER, sb.toString());
+                }
                 throw new IllegalStateException("Enum has create method without String as first parameter: " + mtd.name + mtd.desc);
             }
 
             Type ret = Type.getReturnType(mtd.desc);
             if (!ret.equals(classType)) {
-                LOGGER.fatal(()->new AdvancedLogMessageAdapter(sb-> {
+                if (LOGGER.isErrorEnabled(LogUtils.FATAL_MARKER))
+                {
+                    StringBuilder sb = new StringBuilder();
                     sb.append("Enum has create method with incorrect return type:\n");
                     sb.append("  Enum: ").append(classType.getDescriptor()).append("\n");
                     sb.append("  Target: ").append(mtd.name).append(mtd.desc).append("\n");
                     sb.append("  Found: ").append(ret.getClassName()).append(", Expected: ").append(classType.getClassName());
-                }));
+                    LOGGER.error(LogUtils.FATAL_MARKER, sb.toString());
+                }
                 throw new IllegalStateException("Enum has create method with incorrect return type: " + mtd.name + mtd.desc);
             }
-            
+
             Type[] ctrArgs = new Type[args.length + 1];
             ctrArgs[0] = STRING;
             ctrArgs[1] = Type.INT_TYPE;
@@ -111,23 +118,29 @@ public class RuntimeEnumExtender implements ILaunchPluginService {
             MethodNode ctr = classNode.methods.stream().filter(m -> m.name.equals("<init>") && m.desc.equals(desc)).findFirst().orElse(null);
             if (ctr == null)
             {
-                LOGGER.fatal(()->new AdvancedLogMessageAdapter(sb-> {
+                if (LOGGER.isErrorEnabled(LogUtils.FATAL_MARKER))
+                {
+                    StringBuilder sb = new StringBuilder();
                     sb.append("Enum has create method with no matching constructor:\n");
                     sb.append("  Enum: ").append(classType.getDescriptor()).append("\n");
                     sb.append("  Candidate: ").append(mtd.desc).append("\n");
                     sb.append("  Target: ").append(desc).append("\n");
                     classNode.methods.stream().filter(m -> m.name.equals("<init>")).forEach(m -> sb.append("        : ").append(m.desc).append("\n"));
-                }));
+                    LOGGER.error(LogUtils.FATAL_MARKER, sb.toString());
+                }
                 throw new IllegalStateException("Enum has create method with no matching constructor: " + desc);
             }
 
             if (values == null)
             {
-                LOGGER.fatal(()->new AdvancedLogMessageAdapter(sb-> {
+                if (LOGGER.isErrorEnabled(LogUtils.FATAL_MARKER))
+                {
+                    StringBuilder sb = new StringBuilder();
                     sb.append("Enum has create method but we could not find $VALUES. Found:\n");
                     classNode.fields.stream().filter(f -> (f.access & Opcodes.ACC_STATIC) != 0).
                             forEach(m -> sb.append("  ").append(m.name).append(" ").append(m.desc).append("\n"));
-                }));
+                    LOGGER.error(LogUtils.FATAL_MARKER, sb.toString());
+                }
                 throw new IllegalStateException("Enum has create method but we could not find $VALUES");
             }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/AdvancedLogMessageAdapter.java

@@ -1,48 +0,0 @@
-/*
- * Copyright (c) Forge Development LLC and contributors
- * SPDX-License-Identifier: LGPL-2.1-only
- */
-
-package net.minecraftforge.fml.loading;
-
-import org.apache.logging.log4j.message.Message;
-import org.apache.logging.log4j.util.StringBuilderFormattable;
-
-import java.util.function.Consumer;
-
-public class AdvancedLogMessageAdapter implements Message, StringBuilderFormattable {
-    private static final long serialVersionUID = -8291754833965087436L;
-
-    private static final Object[] EMPTY = new Object[0];
-
-    private final Consumer<StringBuilder> logMessageBuilder;
-
-    public AdvancedLogMessageAdapter(final Consumer<StringBuilder> logMessageBuilder) {
-        this.logMessageBuilder = logMessageBuilder;
-    }
-
-    @Override
-    public String getFormattedMessage() {
-        return "";
-    }
-
-    @Override
-    public String getFormat() {
-        return "";
-    }
-
-    @Override
-    public Object[] getParameters() {
-        return EMPTY;
-    }
-
-    @Override
-    public Throwable getThrowable() {
-        return null;
-    }
-
-    @Override
-    public void formatTo(final StringBuilder buffer) {
-        logMessageBuilder.accept(buffer);
-    }
-}

fmlloader/src/main/java/net/minecraftforge/fml/loading/ClasspathLocatorUtils.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading;
+
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class ClasspathLocatorUtils {
+    
+    private static final Logger LOGGER = LogUtils.getLogger();
+
+    public static Path findJarPathFor(final String resourceName, final String jarName, final URL resource) {
+        try {
+            Path path;
+            final URI uri = resource.toURI();
+            if (uri.getScheme().equals("jar") && uri.getRawSchemeSpecificPart().contains("!/")) {
+                int lastExcl = uri.getRawSchemeSpecificPart().lastIndexOf("!/");
+                path = Paths.get(new URI(uri.getRawSchemeSpecificPart().substring(0, lastExcl)));
+            } else {
+                path = Paths.get(new URI("file://"+uri.getRawSchemeSpecificPart().substring(0, uri.getRawSchemeSpecificPart().length()-resourceName.length())));
+            }
+            //LOGGER.debug(CORE, "Found JAR {} at path {}", jarName, path.toString());
+            return path;
+        } catch (NullPointerException | URISyntaxException e) {
+            LOGGER.error(LogMarkers.SCAN, "Failed to find JAR for class {} - {}", resourceName, jarName);
+            throw new RuntimeException("Unable to locate "+resourceName+" - "+jarName, e);
+        }
+    }
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/ClasspathTransformerDiscoverer.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading;
+
+import cpw.mods.modlauncher.api.NamedPath;
+import cpw.mods.modlauncher.serviceapi.ITransformerDiscoveryService;
+import org.apache.logging.log4j.LogManager;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.*;
+
+public class ClasspathTransformerDiscoverer implements ITransformerDiscoveryService {
+
+    private final List<Path> legacyClasspath = Arrays.stream(System.getProperty("legacyClassPath", "").split(File.pathSeparator)).map(Path::of).toList();
+
+    @Override
+    public List<NamedPath> candidates(Path gameDirectory) {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public List<NamedPath> candidates(final Path gameDirectory, final String launchTarget) {
+        if (launchTarget != null && launchTarget.contains("dev")) {
+            this.scan(gameDirectory);
+        }
+        return List.copyOf(found);
+    }
+
+    private final static List<NamedPath> found = new ArrayList<>();
+
+    public static List<Path> allExcluded() {
+        return found.stream().map(np->np.paths()[0]).toList();
+    }
+    
+    private void scan(final Path gameDirectory) {
+        try {
+            locateTransformers("META-INF/services/cpw.mods.modlauncher.api.ITransformationService");
+            locateTransformers("META-INF/services/net.minecraftforge.forgespi.locating.IModLocator");
+        } catch (IOException e) {
+            LogManager.getLogger().error("Error during discovery of transform services from the classpath", e);
+        }
+    }
+
+    private void locateTransformers(String resource) throws IOException {
+        final Enumeration<URL> resources = ClassLoader.getSystemClassLoader().getResources(resource);
+        while (resources.hasMoreElements()) {
+            URL url = resources.nextElement();
+            Path path = ClasspathLocatorUtils.findJarPathFor(resource, url.toString(), url);
+            if (legacyClasspath.stream().anyMatch(path::equals) || !Files.exists(path) || Files.isDirectory(path))
+                continue;
+            found.add(new NamedPath(path.toUri().toString(), path));
+        }
+    }
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/EarlyLoadingException.java

@@ -47,7 +47,7 @@ public class EarlyLoadingException extends RuntimeException {
         return errorMessages;
     }
 
-    EarlyLoadingException(final String message, final Throwable originalException, List<ExceptionData> errorMessages) {
+    public EarlyLoadingException(final String message, final Throwable originalException, List<ExceptionData> errorMessages) {
         super(message, originalException);
         this.errorMessages = errorMessages;
     }

fmlloader/src/main/java/net/minecraftforge/fml/loading/FMLConfig.java

@@ -10,8 +10,8 @@ import com.electronwill.nightconfig.core.file.CommentedFileConfig;
 import com.electronwill.nightconfig.core.file.FileNotFoundAction;
 import com.electronwill.nightconfig.core.io.ParsingException;
 import com.electronwill.nightconfig.core.io.WritingMode;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
 
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -21,7 +21,7 @@ import static net.minecraftforge.fml.loading.LogMarkers.CORE;
 
 public class FMLConfig
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static FMLConfig INSTANCE = new FMLConfig();
     private static ConfigSpec configSpec = new ConfigSpec();
     static {
@@ -29,6 +29,7 @@ public class FMLConfig
         configSpec.define("maxThreads", -1);
         configSpec.define("versionCheck", Boolean.TRUE);
         configSpec.define("defaultConfigPath",  "defaultconfigs");
+        configSpec.define("disableOptimizedDFU", Boolean.TRUE);
     }
 
     private CommentedFileConfig configData;
@@ -60,12 +61,15 @@ public class FMLConfig
     {
         final Path configFile = FMLPaths.FMLCONFIG.get();
         INSTANCE.loadFrom(configFile);
-        LOGGER.trace(CORE, "Loaded FML config from {}", FMLPaths.FMLCONFIG.get());
-        LOGGER.trace(CORE, "Splash screen is {}", FMLConfig::splashScreenEnabled);
-        LOGGER.trace(CORE, "Max threads for mod loading computed at {}", FMLConfig::loadingThreadCount);
-        LOGGER.trace(CORE, "Version check is {}", FMLConfig::runVersionCheck);
-        LOGGER.trace(CORE, "Default config paths at {}", FMLConfig::defaultConfigPath);
-        FMLPaths.getOrCreateGameRelativePath(Paths.get(FMLConfig.defaultConfigPath()), "default config directory");
+        if (LOGGER.isTraceEnabled(CORE))
+        {
+            LOGGER.trace(CORE, "Loaded FML config from {}", FMLPaths.FMLCONFIG.get());
+            LOGGER.trace(CORE, "Splash screen is {}", FMLConfig.splashScreenEnabled());
+            LOGGER.trace(CORE, "Max threads for mod loading computed at {}", FMLConfig.loadingThreadCount());
+            LOGGER.trace(CORE, "Version check is {}", FMLConfig.runVersionCheck());
+            LOGGER.trace(CORE, "Default config paths at {}", FMLConfig.defaultConfigPath());
+        }
+        FMLPaths.getOrCreateGameRelativePath(Paths.get(FMLConfig.defaultConfigPath()));
     }
 
     public static boolean splashScreenEnabled() {
@@ -85,4 +89,8 @@ public class FMLConfig
     public static String defaultConfigPath() {
         return INSTANCE.configData.<String>getOptional("defaultConfigPath").orElse("defaultconfigs");
     }
+
+    public static boolean isOptimizedDFUDisabled() {
+        return INSTANCE.configData.<Boolean>getOptional("disableOptimizedDFU").orElse(Boolean.TRUE);
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/FMLLoader.java

@@ -5,6 +5,7 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.Launcher;
 import cpw.mods.modlauncher.api.*;
 import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
@@ -21,8 +22,7 @@ import net.minecraftforge.fml.loading.targets.CommonLaunchHandler;
 import net.minecraftforge.forgespi.Environment;
 import net.minecraftforge.forgespi.coremod.ICoreModProvider;
 import org.apache.commons.lang3.tuple.Pair;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -35,7 +35,7 @@ import static net.minecraftforge.fml.loading.LogMarkers.SCAN;
 
 public class FMLLoader
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static AccessTransformerService accessTransformer;
     private static ModDiscoverer modDiscoverer;
     private static ICoreModProvider coreModProvider;
@@ -62,47 +62,50 @@ public class FMLLoader
         final Package modLauncherPackage = ITransformationService.class.getPackage();
         LOGGER.debug(CORE,"FML found ModLauncher version : {}", modLauncherPackage.getImplementationVersion());
         if (!modLauncherPackage.isCompatibleWith("4.0")) {
-            LOGGER.fatal(CORE,"Found incompatible ModLauncher specification : {}, version {} from {}", modLauncherPackage.getSpecificationVersion(), modLauncherPackage.getImplementationVersion(), modLauncherPackage.getImplementationVendor());
+            LOGGER.error(CORE, "Found incompatible ModLauncher specification : {}, version {} from {}", modLauncherPackage.getSpecificationVersion(), modLauncherPackage.getImplementationVersion(), modLauncherPackage.getImplementationVendor());
             throw new IncompatibleEnvironmentException("Incompatible modlauncher found "+modLauncherPackage.getSpecificationVersion());
         }
 
+        // Allows us to communicate properties with other services through ModLauncher
+        setupBlackboardKeys();
+
         accessTransformer = (AccessTransformerService) environment.findLaunchPlugin("accesstransformer").orElseThrow(()-> {
-            LOGGER.fatal(CORE,"Access Transformer library is missing, we need this to run");
+            LOGGER.error(CORE, "Access Transformer library is missing, we need this to run");
             return new IncompatibleEnvironmentException("Missing AccessTransformer, cannot run");
         });
 
         final Package atPackage = accessTransformer.getClass().getPackage();
         LOGGER.debug(CORE,"FML found AccessTransformer version : {}", atPackage.getImplementationVersion());
         if (!atPackage.isCompatibleWith("1.0")) {
-            LOGGER.fatal(CORE,"Found incompatible AccessTransformer specification : {}, version {} from {}", atPackage.getSpecificationVersion(), atPackage.getImplementationVersion(), atPackage.getImplementationVendor());
+            LOGGER.error(CORE, "Found incompatible AccessTransformer specification : {}, version {} from {}", atPackage.getSpecificationVersion(), atPackage.getImplementationVersion(), atPackage.getImplementationVendor());
             throw new IncompatibleEnvironmentException("Incompatible accesstransformer found "+atPackage.getSpecificationVersion());
         }
 
         eventBus = environment.findLaunchPlugin("eventbus").orElseThrow(()-> {
-            LOGGER.fatal(CORE,"Event Bus library is missing, we need this to run");
+            LOGGER.error(CORE, "Event Bus library is missing, we need this to run");
             return new IncompatibleEnvironmentException("Missing EventBus, cannot run");
         });
 
         final Package eventBusPackage = eventBus.getClass().getPackage();
         LOGGER.debug(CORE,"FML found EventBus version : {}", eventBusPackage.getImplementationVersion());
         if (!eventBusPackage.isCompatibleWith("1.0")) {
-            LOGGER.fatal(CORE,"Found incompatible EventBus specification : {}, version {} from {}", eventBusPackage.getSpecificationVersion(), eventBusPackage.getImplementationVersion(), eventBusPackage.getImplementationVendor());
+            LOGGER.error(CORE, "Found incompatible EventBus specification : {}, version {} from {}", eventBusPackage.getSpecificationVersion(), eventBusPackage.getImplementationVersion(), eventBusPackage.getImplementationVendor());
             throw new IncompatibleEnvironmentException("Incompatible eventbus found "+eventBusPackage.getSpecificationVersion());
         }
 
         runtimeDistCleaner = (RuntimeDistCleaner)environment.findLaunchPlugin("runtimedistcleaner").orElseThrow(()-> {
-            LOGGER.fatal(CORE,"Dist Cleaner is missing, we need this to run");
+            LOGGER.error(CORE, "Dist Cleaner is missing, we need this to run");
             return new IncompatibleEnvironmentException("Missing DistCleaner, cannot run!");
         });
         LOGGER.debug(CORE, "Found Runtime Dist Cleaner");
 
-        var coreModProviders = ServiceLoaderUtils.streamWithErrorHandling(ServiceLoader.load(FMLLoader.class.getModule().getLayer(), ICoreModProvider.class), sce -> LOGGER.fatal(CORE, "Failed to load a coremod library, expect problems", sce)).toList();
+        var coreModProviders = ServiceLoaderUtils.streamWithErrorHandling(ServiceLoader.load(FMLLoader.class.getModule().getLayer(), ICoreModProvider.class), sce -> LOGGER.error(CORE, "Failed to load a coremod library, expect problems", sce)).toList();
 
         if (coreModProviders.isEmpty()) {
-            LOGGER.fatal(CORE, "Found no coremod provider. Cannot run");
+            LOGGER.error(CORE, "Found no coremod provider. Cannot run");
             throw new IncompatibleEnvironmentException("No coremod library found");
         } else if (coreModProviders.size() > 1) {
-            LOGGER.fatal(CORE, "Found multiple coremod providers : {}. Cannot run", coreModProviders.stream().map(p -> p.getClass().getName()).collect(Collectors.toList()));
+            LOGGER.error(CORE, "Found multiple coremod providers : {}. Cannot run", coreModProviders.stream().map(p -> p.getClass().getName()).collect(Collectors.toList()));
             throw new IncompatibleEnvironmentException("Multiple coremod libraries found");
         }
 
@@ -114,7 +117,7 @@ public class FMLLoader
         LOGGER.debug(CORE, "Found ForgeSPI package implementation version {}", Environment.class.getPackage().getImplementationVersion());
         LOGGER.debug(CORE, "Found ForgeSPI package specification {}", Environment.class.getPackage().getSpecificationVersion());
         if (Integer.parseInt(Environment.class.getPackage().getSpecificationVersion()) < 2) {
-            LOGGER.fatal(CORE, "Found an out of date ForgeSPI implementation: {}, loading cannot continue", Environment.class.getPackage().getSpecificationVersion());
+            LOGGER.error(CORE, "Found an out of date ForgeSPI implementation: {}, loading cannot continue", Environment.class.getPackage().getSpecificationVersion());
             throw new IncompatibleEnvironmentException("ForgeSPI is out of date, we cannot continue");
         }
 
@@ -122,11 +125,17 @@ public class FMLLoader
             Class.forName("com.electronwill.nightconfig.core.Config", false, environment.getClass().getClassLoader());
             Class.forName("com.electronwill.nightconfig.toml.TomlFormat", false, environment.getClass().getClassLoader());
         } catch (ClassNotFoundException e) {
-            LOGGER.fatal(CORE, "Failed to load NightConfig");
+            LOGGER.error(CORE, "Failed to load NightConfig");
             throw new IncompatibleEnvironmentException("Missing NightConfig");
         }
     }
 
+    private static void setupBlackboardKeys() {
+        LOGGER.debug(CORE, "Requesting CoreMods to not apply the fix for ASMAPI.findFirstInstructionBefore by default");
+        var blackboardKey = TypesafeMap.Key.getOrCreate(Launcher.INSTANCE.blackboard(), "coremods.use_old_findFirstInstructionBefore", Boolean.class);
+        Launcher.INSTANCE.blackboard().<Boolean>computeIfAbsent(blackboardKey, k -> true);
+    }
+
     static void setupLaunchHandler(final IEnvironment environment, final Map<String, Object> arguments)
     {
         final String launchTarget = environment.getProperty(IEnvironment.Keys.LAUNCHTARGET.get()).orElse("MISSING");
@@ -134,12 +143,12 @@ public class FMLLoader
         final Optional<ILaunchHandlerService> launchHandler = environment.findLaunchHandler(launchTarget);
         LOGGER.debug(CORE, "Using {} as launch service", launchTarget);
         if (launchHandler.isEmpty()) {
-            LOGGER.fatal(CORE,"Missing LaunchHandler {}, cannot continue", launchTarget);
+            LOGGER.error(CORE, "Missing LaunchHandler {}, cannot continue", launchTarget);
             throw new RuntimeException("Missing launch handler: " + launchTarget);
         }
 
         if (!(launchHandler.get() instanceof CommonLaunchHandler)) {
-            LOGGER.fatal(CORE, "Incompatible Launch handler found - type {}, cannot continue", launchHandler.get().getClass().getName());
+            LOGGER.error(CORE, "Incompatible Launch handler found - type {}, cannot continue", launchHandler.get().getClass().getName());
             throw new RuntimeException("Incompatible launch handler found");
         }
         commonLaunchHandler = (CommonLaunchHandler)launchHandler.get();

fmlloader/src/main/java/net/minecraftforge/fml/loading/FMLPaths.java

@@ -5,10 +5,12 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.IEnvironment;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
+import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Arrays;
@@ -22,7 +24,7 @@ public enum FMLPaths
     CONFIGDIR("config"),
     FMLCONFIG(false, CONFIGDIR, "fml.toml");
 
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private final Path relativePath;
     private final boolean isDirectory;
     private Path absolutePath;
@@ -57,16 +59,41 @@ public enum FMLPaths
         for (FMLPaths path : FMLPaths.values())
         {
             path.absolutePath = rootPath.resolve(path.relativePath).toAbsolutePath().normalize();
-            if (path.isDirectory)
+            if (path.isDirectory && !Files.isDirectory(path.absolutePath))
             {
-                FileUtils.getOrCreateDirectory(path.absolutePath, path.name());
+                try {
+                   Files.createDirectories(path.absolutePath);
+                } catch (IOException e) {
+                   throw new RuntimeException(e);
+                }
+            }
+            if (LOGGER.isDebugEnabled(CORE))
+            {
+                LOGGER.debug(CORE, "Path {} is {}", path, path.absolutePath);
             }
-            LOGGER.debug(CORE,"Path {} is {}", ()-> path, ()-> path.absolutePath);
         }
     }
 
+    /**
+     * @deprecated Use {@link #getOrCreateGameRelativePath(Path)} instead.
+     */
+    @Deprecated(forRemoval = true, since = "1.19.4")
     public static Path getOrCreateGameRelativePath(Path path, String name) {
-        return FileUtils.getOrCreateDirectory(FMLPaths.GAMEDIR.get().resolve(path), name);
+        return getOrCreateGameRelativePath(path);
+    }
+
+    public static Path getOrCreateGameRelativePath(Path path) {
+        Path gameFolderPath = FMLPaths.GAMEDIR.get().resolve(path);
+
+        if (!Files.isDirectory(gameFolderPath)) {
+            try {
+                Files.createDirectories(gameFolderPath);
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        }
+
+        return gameFolderPath;
     }
 
     public Path relative() {

fmlloader/src/main/java/net/minecraftforge/fml/loading/FMLServiceProvider.java

@@ -5,14 +5,14 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.*;
 import joptsimple.ArgumentAcceptingOptionSpec;
 import joptsimple.OptionSpecBuilder;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.forgespi.Environment;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
 import org.jetbrains.annotations.NotNull;
+import org.slf4j.Logger;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -26,7 +26,7 @@ import static net.minecraftforge.fml.loading.LogMarkers.CORE;
 
 public class FMLServiceProvider implements ITransformationService
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private ArgumentAcceptingOptionSpec<String> modsOption;
     private ArgumentAcceptingOptionSpec<String> modListsOption;
     private ArgumentAcceptingOptionSpec<String> mavenRootsOption;

fmlloader/src/main/java/net/minecraftforge/fml/loading/FileUtils.java

@@ -5,41 +5,32 @@
 
 package net.minecraftforge.fml.loading;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
 
+import java.io.File;
 import java.io.IOException;
-import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
-import static net.minecraftforge.fml.loading.LogMarkers.CORE;
-
 public class FileUtils
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
 
+   /**
+    * @deprecated Use normal Java NIO methods instead
+    */
+    @Deprecated(forRemoval = true, since = "1.19.4")
     public static Path getOrCreateDirectory(Path dirPath, String dirLabel) {
-        if (!Files.isDirectory(dirPath.getParent())) {
-            getOrCreateDirectory(dirPath.getParent(), "parent of "+dirLabel);
-        }
         if (!Files.isDirectory(dirPath))
         {
-            LOGGER.debug(CORE,"Making {} directory : {}", dirLabel, dirPath);
             try {
-                Files.createDirectory(dirPath);
+                Files.createDirectories(dirPath);
             } catch (IOException e) {
-                if (e instanceof FileAlreadyExistsException) {
-                    LOGGER.fatal(CORE,"Failed to create {} directory - there is a file in the way", dirLabel);
-                } else {
-                    LOGGER.fatal(CORE,"Problem with creating {} directory (Permissions?)", dirLabel, e);
-                }
                 throw new RuntimeException("Problem creating directory", e);
             }
-            LOGGER.debug(CORE,"Created {} directory : {}", dirLabel, dirPath);
-        } else {
-            LOGGER.debug(CORE,"Found existing {} directory : {}", dirLabel, dirPath);
         }
+
         return dirPath;
     }
 
@@ -53,4 +44,16 @@ public class FileUtils
             return "";
         }
     }
+
+    public static boolean matchFileName(String path, String... matches) {
+        // Extract file name from path
+        String name = path.substring(Math.min(path.lastIndexOf(File.separatorChar) + 1, path.length()));
+        // Check if it contains any of the desired keywords
+        for (String match : matches) {
+            if (name.contains(match)) {
+                return true;
+            }
+        }
+        return false;
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/LanguageLoadingProvider.java

@@ -5,6 +5,7 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.Launcher;
 import cpw.mods.modlauncher.api.IModuleLayerManager;
 import cpw.mods.modlauncher.util.ServiceLoaderUtils;
@@ -12,11 +13,10 @@ import net.minecraftforge.fml.loading.progress.StartupMessageManager;
 import net.minecraftforge.forgespi.language.IModLanguageProvider;
 import net.minecraftforge.fml.loading.moddiscovery.ExplodedDirectoryLocator;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
 import org.apache.maven.artifact.versioning.ArtifactVersion;
 import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
 import org.apache.maven.artifact.versioning.VersionRange;
+import org.slf4j.Logger;
 
 import java.net.URISyntaxException;
 import java.nio.file.Files;
@@ -38,7 +38,7 @@ import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
 
 public class LanguageLoadingProvider
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private final List<IModLanguageProvider> languageProviders = new ArrayList<>();
     private final ServiceLoader<IModLanguageProvider> serviceLoader;
     private final Map<String, ModLanguageWrapper> languageProviderMap = new HashMap<>();
@@ -81,7 +81,7 @@ public class LanguageLoadingProvider
         loadLanguageProviders();
     }
     private void loadLanguageProviders() {
-        LOGGER.debug(CORE, "Found {} language providers", ServiceLoaderUtils.streamServiceLoader(()->serviceLoader, sce->LOGGER.fatal("Problem with language loaders")).count());
+        LOGGER.debug(CORE, "Found {} language providers", ServiceLoaderUtils.streamServiceLoader(()->serviceLoader, sce->LOGGER.error("Problem with language loaders")).count());
         serviceLoader.forEach(languageProviders::add);
 
         languageProviders.forEach(lp -> {
@@ -94,7 +94,7 @@ public class LanguageLoadingProvider
             Optional<String> implementationVersion = JarVersionLookupHandler.getImplementationVersion(lp.getClass());
             String impl = implementationVersion.orElse(Files.isDirectory(lpPath) ? FMLLoader.versionInfo().forgeVersion().split("\\.")[0] : null);
             if (impl == null) {
-                LOGGER.fatal(CORE, "Found unversioned language provider {}", lp.name());
+                LOGGER.error(CORE, "Found unversioned language provider {}", lp.name());
                 throw new RuntimeException("Failed to find implementation version for language provider "+ lp.name());
             }
             LOGGER.debug(CORE, "Found language provider {}, version {}", lp.name(), impl);
@@ -134,7 +134,7 @@ public class LanguageLoadingProvider
     }
 
     public IModLanguageProvider findLanguage(ModFile mf, String modLoader, VersionRange modLoaderVersion) {
-        final String languageFileName = mf.getLocator() instanceof ExplodedDirectoryLocator ? "in-development" : mf.getFileName();
+        final String languageFileName = mf.getProvider() instanceof ExplodedDirectoryLocator ? "in-development" : mf.getFileName();
         final ModLanguageWrapper mlw = languageProviderMap.get(modLoader);
         if (mlw == null) {
             LOGGER.error(LOADING,"Missing language {} version {} wanted by {}", modLoader, modLoaderVersion, languageFileName);

fmlloader/src/main/java/net/minecraftforge/fml/loading/LauncherVersion.java

@@ -5,13 +5,13 @@
 
 package net.minecraftforge.fml.loading;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
 
 import static net.minecraftforge.fml.loading.LogMarkers.CORE;
 
 public class LauncherVersion {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static final String launcherVersion;
 
     static {

fmlloader/src/main/java/net/minecraftforge/fml/loading/LibraryFinder.java

@@ -5,14 +5,14 @@
 
 package net.minecraftforge.fml.loading;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import com.mojang.logging.LogUtils;
+import org.slf4j.Logger;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
 
 public class LibraryFinder {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static Path libsPath;
     static Path findLibsPath() {
         if (libsPath == null) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/LoadingModList.java

@@ -10,11 +10,18 @@ import net.minecraftforge.fml.loading.moddiscovery.BackgroundScanHandler;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
 import net.minecraftforge.fml.loading.moddiscovery.ModInfo;
+import net.minecraftforge.forgespi.locating.IModFile;
 
 import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
 import java.util.stream.Collectors;
 
 /**
@@ -28,7 +35,7 @@ public class LoadingModList
     private final List<ModInfo> sortedList;
     private final Map<String, ModFileInfo> fileById;
     private final List<EarlyLoadingException> preLoadErrors;
-    private List<ModFile> brokenFiles;
+    private List<IModFile> brokenFiles;
 
     private LoadingModList(final List<ModFile> modFiles, final List<ModInfo> sortedList)
     {
@@ -154,11 +161,11 @@ public class LoadingModList
         return preLoadErrors;
     }
 
-    public void setBrokenFiles(final List<ModFile> brokenFiles) {
+    public void setBrokenFiles(final List<IModFile> brokenFiles) {
         this.brokenFiles = brokenFiles;
     }
 
-    public List<ModFile> getBrokenFiles() {
+    public List<IModFile> getBrokenFiles() {
         return this.brokenFiles;
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/LogMarkers.java

@@ -5,12 +5,12 @@
 
 package net.minecraftforge.fml.loading;
 
-import org.apache.logging.log4j.Marker;
-import org.apache.logging.log4j.MarkerManager;
+import org.slf4j.Marker;
+import org.slf4j.MarkerFactory;
 
 public class LogMarkers {
-    public static final Marker CORE = MarkerManager.getMarker("CORE");
-    public static final Marker LOADING = MarkerManager.getMarker("LOADING");
-    public static final Marker SCAN = MarkerManager.getMarker("SCAN");
-    public static final Marker SPLASH = MarkerManager.getMarker("SPLASH");
+    public static final Marker CORE = MarkerFactory.getMarker("CORE");
+    public static final Marker LOADING = MarkerFactory.getMarker("LOADING");
+    public static final Marker SCAN = MarkerFactory.getMarker("SCAN");
+    public static final Marker SPLASH = MarkerFactory.getMarker("SPLASH");
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/MCPNamingService.java

@@ -5,10 +5,10 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.INameMappingService;
 import org.apache.commons.lang3.tuple.Pair;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -20,7 +20,7 @@ import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 
 public class MCPNamingService implements INameMappingService {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private HashMap<String, String> methods;
     private HashMap<String, String> fields;
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/ModDirTransformerDiscoverer.java

@@ -5,20 +5,29 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
+import cpw.mods.jarhandling.SecureJar;
 import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
 import cpw.mods.modlauncher.api.NamedPath;
 import cpw.mods.modlauncher.serviceapi.ITransformerDiscoveryService;
-import org.apache.logging.log4j.LogManager;
+import org.slf4j.Logger;
 
-import java.io.File;
 import java.io.IOException;
+import java.lang.module.ModuleDescriptor;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.zip.ZipFile;
+import java.util.Set;
 
 public class ModDirTransformerDiscoverer implements ITransformerDiscoveryService {
+    private static final Logger LOGGER = LogUtils.getLogger();
+    private static final Set<String> SERVICES = Set.of(
+        "cpw.mods.modlauncher.api.ITransformationService",
+        "net.minecraftforge.forgespi.locating.IModLocator",
+        "net.minecraftforge.forgespi.locating.IDependencyLocator"
+    );
+
     @Override
     public List<NamedPath> candidates(final Path gameDirectory) {
         ModDirTransformerDiscoverer.scan(gameDirectory);
@@ -40,7 +49,7 @@ public class ModDirTransformerDiscoverer implements ITransformerDiscoveryService
         try (var walk = Files.walk(modsDir, 1)){
             walk.forEach(ModDirTransformerDiscoverer::visitFile);
         } catch (IOException | IllegalStateException ioe) {
-            LogManager.getLogger().error("Error during early discovery", ioe);
+            LOGGER.error("Error during early discovery", ioe);
         }
     }
 
@@ -48,14 +57,11 @@ public class ModDirTransformerDiscoverer implements ITransformerDiscoveryService
         if (!Files.isRegularFile(path)) return;
         if (!path.toString().endsWith(".jar")) return;
         if (LamdbaExceptionUtils.uncheck(() -> Files.size(path)) == 0) return;
-        try (ZipFile zf = new ZipFile(new File(path.toUri()))) {
-            if (zf.getEntry("META-INF/services/cpw.mods.modlauncher.api.ITransformationService") != null) {
-                found.add(new NamedPath(zf.getName(), path));
-            } else if (zf.getEntry("META-INF/services/net.minecraftforge.forgespi.locating.IModLocator") != null) {
-                found.add(new NamedPath(zf.getName(), path));
-            }
-        } catch (IOException ioe) {
-            LogManager.getLogger().error("Zip Error when loading jar file {}", path, ioe);
-        }
+
+        SecureJar jar = SecureJar.from(path);
+        jar.moduleDataProvider().descriptor().provides().stream()
+            .map(ModuleDescriptor.Provides::service)
+            .filter(SERVICES::contains)
+            .forEach(s -> found.add(new NamedPath(s, path)));
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/ModJarURLHandler.java

@@ -5,9 +5,9 @@
 
 package net.minecraftforge.fml.loading;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -24,7 +24,7 @@ import static net.minecraftforge.fml.loading.LogMarkers.CORE;
 
 public class ModJarURLHandler extends URLStreamHandler
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     // modjar://modid/path/to/file
     @Override
     protected URLConnection openConnection(URL url) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/ModSorter.java

@@ -7,6 +7,7 @@ package net.minecraftforge.fml.loading;
 
 import com.google.common.graph.GraphBuilder;
 import com.google.common.graph.MutableGraph;
+import com.mojang.logging.LogUtils;
 import cpw.mods.jarhandling.SecureJar;
 import net.minecraftforge.fml.loading.moddiscovery.MinecraftLocator;
 import net.minecraftforge.forgespi.language.IModFileInfo;
@@ -17,11 +18,9 @@ import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
 import net.minecraftforge.fml.loading.moddiscovery.ModInfo;
 import net.minecraftforge.fml.loading.toposort.CyclePresentException;
 import net.minecraftforge.fml.loading.toposort.TopologicalSort;
-import net.minecraftforge.forgespi.locating.IModFile;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
 import org.apache.maven.artifact.versioning.ArtifactVersion;
 import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
+import org.slf4j.Logger;
 
 import java.util.*;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -35,15 +34,16 @@ import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
 
 public class ModSorter
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
+    private final UniqueModListBuilder uniqueModListBuilder;
     private List<ModFile> modFiles;
     private List<ModInfo> sortedList;
-    private Map<String, ModInfo> modIdNameLookup;
+    private Map<String, IModInfo> modIdNameLookup;
     private List<ModFile> systemMods;
 
     private ModSorter(final List<ModFile> modFiles)
     {
-        this.modFiles = modFiles;
+        this.uniqueModListBuilder = new UniqueModListBuilder(modFiles);
     }
 
     public static LoadingModList sort(List<ModFile> mods, final List<ExceptionData> errors)
@@ -78,11 +78,12 @@ public class ModSorter
         // lambdas are identity based, so sorting them is impossible unless you hold reference to them
         final MutableGraph<ModFileInfo> graph = GraphBuilder.directed().build();
         AtomicInteger counter = new AtomicInteger();
-        Map<IModFileInfo, Integer> infos = modFiles.stream()
+        Map<ModFileInfo, Integer> infos = modFiles.stream()
                 .map(ModFile::getModFileInfo)
                 .filter(ModFileInfo.class::isInstance)
+                .map(ModFileInfo.class::cast)
                 .collect(toMap(Function.identity(), e -> counter.incrementAndGet()));
-        infos.keySet().forEach(i -> graph.addNode((ModFileInfo) i));
+        infos.keySet().forEach(graph::addNode);
         modFiles.stream()
                 .map(ModFile::getModInfos)
                 .<IModInfo>mapMulti(Iterable::forEach)
@@ -98,11 +99,10 @@ public class ModSorter
         catch (CyclePresentException e)
         {
             Set<Set<ModFileInfo>> cycles = e.getCycles();
-            LOGGER.error(LOADING, () -> new AdvancedLogMessageAdapter(buffer ->
-                    buffer.append("Mod Sorting failed.\n")
-                    .append("Detected Cycles: ")
-                    .append(cycles)
-                    .append('\n')));
+            if (LOGGER.isErrorEnabled(LOADING))
+            {
+                LOGGER.error(LOADING, "Mod Sorting failed.\nDetected Cycles: {}\n", cycles);
+            }
             var dataList = cycles.stream()
                     .<ModFileInfo>mapMulti(Iterable::forEach)
                     .<IModInfo>mapMulti((mf,c)->mf.getMods().forEach(c))
@@ -125,10 +125,9 @@ public class ModSorter
     private void addDependency(MutableGraph<ModFileInfo> topoGraph, IModInfo.ModVersion dep)
     {
         final ModFileInfo self = (ModFileInfo)dep.getOwner().getOwningFile();
-        final ModInfo targetModInfo = modIdNameLookup.get(dep.getModId());
+        final IModInfo targetModInfo = modIdNameLookup.get(dep.getModId());
         // soft dep that doesn't exist. Just return. No edge required.
-        if (targetModInfo == null) return;
-        final ModFileInfo target = targetModInfo.getOwningFile();
+        if (targetModInfo == null || !(targetModInfo.getOwningFile() instanceof final ModFileInfo target)) return;
         if (self == target)
             return; // in case a jar has two mods that have dependencies between
         switch (dep.getOrdering()) {
@@ -139,19 +138,32 @@ public class ModSorter
 
     private void buildUniqueList()
     {
-        // Collect mod files by module name. This will be used for deduping purposes
-        final Map<String, List<IModFile>> modFilesByFirstId = modFiles.stream()
-                .collect(groupingBy(mf -> mf.getModFileInfo().moduleName()));
+        final UniqueModListBuilder.UniqueModListData uniqueModListData = uniqueModListBuilder.buildUniqueList();
 
+        this.modFiles = uniqueModListData.modFiles();
+
+        detectSystemMods(uniqueModListData.modFilesByFirstId());
+
+        modIdNameLookup = uniqueModListData.modFilesByFirstId().entrySet().stream()
+                .filter(e -> !e.getValue().get(0).getModInfos().isEmpty())
+                .collect(Collectors.toMap(
+                    Map.Entry::getKey,
+                    e -> e.getValue().get(0).getModInfos().get(0)
+                  ));
+    }
+
+    private void detectSystemMods(final Map<String, List<ModFile>> modFilesByFirstId)
+    {
         // Capture system mods (ex. MC, Forge) here, so we can keep them for later
         final Set<String> systemMods = new HashSet<>();
         // The minecraft mod is always a system mod
         systemMods.add("minecraft");
         // Find mod file from MinecraftLocator to define the system mods
         modFiles.stream()
-                .filter(modFile -> modFile.getLocator().getClass() == MinecraftLocator.class)
+                .filter(modFile -> modFile.getProvider().getClass() == MinecraftLocator.class)
                 .map(ModFile::getSecureJar)
-                .map(SecureJar::getManifest)
+                .map(SecureJar::moduleDataProvider)
+                .map(SecureJar.ModuleDataProvider::getManifest)
                 .map(Manifest::getMainAttributes)
                 .map(mf -> mf.getValue("FML-System-Mods"))
                 .filter(Objects::nonNull)
@@ -169,47 +181,6 @@ public class ModSorter
                 throw new IllegalStateException("Failed to find system mod: " + systemMod);
             }
         }
-
-        // Select the newest by artifact version sorting of non-unique files thus identified
-        this.modFiles = modFilesByFirstId.entrySet().stream()
-                .map(this::selectNewestModInfo)
-                .map(Map.Entry::getValue)
-                .map(ModFile.class::cast)
-                .collect(toList());
-
-        // Transform to the full mod id list
-        final Map<String, List<ModInfo>> modIds = modFiles.stream()
-                .map(ModFile::getModInfos)
-                .flatMap(Collection::stream)
-                .map(ModInfo.class::cast)
-                .collect(groupingBy(IModInfo::getModId));
-
-        // Its theoretically possible that some mod has somehow moved an id to a secondary place, thus causing a dupe.
-        // We can't handle this
-        final List<ModInfo> dupedMods = modIds.values().stream()
-                .filter(modInfos -> modInfos.size() > 1)
-                .map(modInfos -> modInfos.get(0))
-                .toList();
-
-        if (!dupedMods.isEmpty()) {
-            final List<EarlyLoadingException.ExceptionData> duplicateModErrors = dupedMods.stream()
-                    .map(dm -> new EarlyLoadingException.ExceptionData("fml.modloading.dupedmod",
-                            dm, Objects.toString(dm))).toList();
-            throw new EarlyLoadingException("Duplicate mods found", null,  duplicateModErrors);
-        }
-
-        modIdNameLookup = modIds.entrySet().stream()
-                .collect(toMap(Map.Entry::getKey, e -> e.getValue().get(0)));
-    }
-
-    private Map.Entry<String, IModFile> selectNewestModInfo(Map.Entry<String, List<IModFile>> fullList) {
-        List<IModFile> modInfoList = fullList.getValue();
-        if (modInfoList.size() > 1) {
-            LOGGER.debug("Found {} mods for first modid {}, selecting most recent based on version data", modInfoList.size(), fullList.getKey());
-            modInfoList.sort(Comparator.<IModFile, ArtifactVersion>comparing(mf -> mf.getModInfos().get(0).getVersion()).reversed());
-            LOGGER.debug("Selected file {} for modid {} with version {}", modInfoList.get(0).getFileName(), fullList.getKey(), modInfoList.get(0).getModInfos().get(0).getVersion());
-        }
-        return Map.entry(fullList.getKey(), modInfoList.get(0));
     }
 
     private List<EarlyLoadingException.ExceptionData> verifyDependencyVersions()
@@ -239,10 +210,24 @@ public class ModSorter
 
         if (!missingVersions.isEmpty()) {
             if (mandatoryMissing > 0) {
-                LOGGER.error(LOADING, "Missing mandatory dependencies: {}", missingVersions.stream().filter(IModInfo.ModVersion::isMandatory).map(IModInfo.ModVersion::getModId).collect(Collectors.joining(", ")));
+                LOGGER.error(
+                        LOADING,
+                        "Missing or unsupported mandatory dependencies:\n{}",
+                        missingVersions.stream()
+                                .filter(IModInfo.ModVersion::isMandatory)
+                                .map(ver -> formatDependencyError(ver, modVersions))
+                                .collect(Collectors.joining("\n"))
+                );
             }
             if (missingVersions.size() - mandatoryMissing > 0) {
-                LOGGER.error(LOADING, "Unsupported installed optional dependencies: {}", missingVersions.stream().filter(ver -> !ver.isMandatory()).map(IModInfo.ModVersion::getModId).collect(Collectors.joining(", ")));
+                LOGGER.error(
+                        LOADING,
+                        "Unsupported installed optional dependencies:\n{}",
+                        missingVersions.stream()
+                                .filter(ver -> !ver.isMandatory())
+                                .map(ver -> formatDependencyError(ver, modVersions))
+                                .collect(Collectors.joining("\n"))
+                );
             }
 
             return missingVersions.stream()
@@ -254,6 +239,18 @@ public class ModSorter
         return Collections.emptyList();
     }
 
+    private static String formatDependencyError(IModInfo.ModVersion dependency, Map<String, ArtifactVersion> modVersions)
+    {
+        ArtifactVersion installed = modVersions.get(dependency.getModId());
+        return String.format(
+                "\tMod ID: '%s', Requested by: '%s', Expected range: '%s', Actual version: '%s'",
+                dependency.getModId(),
+                dependency.getOwner().getModId(),
+                dependency.getVersionRange(),
+                installed != null ? installed.toString() : "[MISSING]"
+        );
+    }
+
     private boolean modVersionNotContained(final IModInfo.ModVersion mv, final Map<String, ArtifactVersion> modVersions)
     {
         return !(VersionSupportMatrix.testVersionSupportMatrix(mv.getVersionRange(), mv.getModId(), "mod", (modId, range) -> modVersions.containsKey(modId) &&

fmlloader/src/main/java/net/minecraftforge/fml/loading/RuntimeDistCleaner.java

@@ -16,14 +16,11 @@ import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 import com.google.common.collect.Streams;
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
 import net.minecraftforge.api.distmarker.Dist;
 import net.minecraftforge.api.distmarker.OnlyIn;
 import net.minecraftforge.api.distmarker.OnlyIns;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-import org.apache.logging.log4j.Marker;
-import org.apache.logging.log4j.MarkerManager;
 import org.objectweb.asm.Handle;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;
@@ -33,11 +30,14 @@ import org.objectweb.asm.tree.AnnotationNode;
 import org.objectweb.asm.tree.ClassNode;
 import org.objectweb.asm.tree.FieldNode;
 import org.objectweb.asm.tree.MethodNode;
+import org.slf4j.Logger;
+import org.slf4j.Marker;
+import org.slf4j.MarkerFactory;
 
 public class RuntimeDistCleaner implements ILaunchPluginService
 {
-    private static final Logger LOGGER = LogManager.getLogger();
-    private static final Marker DISTXFORM = MarkerManager.getMarker("DISTXFORM");
+    private static final Logger LOGGER = LogUtils.getLogger();
+    private static final Marker DISTXFORM = MarkerFactory.getMarker("DISTXFORM");
     private static String DIST;
     private static final String ONLYIN = Type.getDescriptor(OnlyIn.class);
     private static final String ONLYINS = Type.getDescriptor(OnlyIns.class);
@@ -53,7 +53,7 @@ public class RuntimeDistCleaner implements ILaunchPluginService
         AtomicBoolean changes = new AtomicBoolean();
         if (remove(classNode.visibleAnnotations, DIST))
         {
-            LOGGER.fatal(DISTXFORM, "Attempted to load class {} for invalid dist {}", classNode.name, DIST);
+            LOGGER.error(DISTXFORM, "Attempted to load class {} for invalid dist {}", classNode.name, DIST);
             throw new RuntimeException("Attempted to load class "+ classNode.name  + " for invalid dist "+ DIST);
         }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/TracingPrintStream.java

@@ -5,8 +5,7 @@
 
 package net.minecraftforge.fml.loading;
 
-import org.apache.logging.log4j.Logger;
-
+import org.slf4j.Logger;
 import java.io.PrintStream;
 
 /**

fmlloader/src/main/java/net/minecraftforge/fml/loading/UniqueModListBuilder.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading;
+
+import com.mojang.logging.LogUtils;
+import net.minecraftforge.fml.loading.moddiscovery.ModFile;
+import net.minecraftforge.forgespi.language.IModInfo;
+import org.apache.maven.artifact.versioning.ArtifactVersion;
+import org.slf4j.Logger;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.joining;
+import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
+
+public class UniqueModListBuilder
+{
+    private final static Logger LOGGER = LogUtils.getLogger();
+
+    private final List<ModFile> modFiles;
+
+    public UniqueModListBuilder(final List<ModFile> modFiles) {this.modFiles = modFiles;}
+
+    public UniqueModListData buildUniqueList()
+    {
+        List<ModFile> uniqueModList;
+        List<ModFile> uniqueLibListWithVersion;
+
+        // Collect mod files by module name. This will be used for deduping purposes
+        final Map<String, List<ModFile>> modFilesByFirstId = modFiles.stream()
+                .filter(mf -> mf.getModFileInfo() != null)
+                .collect(groupingBy(UniqueModListBuilder::getModId));
+
+        final Map<String, List<ModFile>> libFilesWithVersionByModuleName = modFiles.stream()
+                .filter(mf -> mf.getModFileInfo() == null)
+                .collect(groupingBy(UniqueModListBuilder::getModId));
+
+        // Select the newest by artifact version sorting of non-unique files thus identified
+        uniqueModList = modFilesByFirstId.entrySet().stream()
+                .map(this::selectNewestModInfo)
+                .toList();
+
+        // Select the newest by artifact version sorting of non-unique files thus identified
+        uniqueLibListWithVersion = libFilesWithVersionByModuleName.entrySet().stream()
+                .map(this::selectNewestModInfo)
+                .toList();
+
+        // Transform to the full mod id list
+        final Map<String, List<IModInfo>> modIds = uniqueModList.stream()
+                .filter(mf -> mf.getModFileInfo() != null) //Filter out non-mod files, we don't care about those for now.....
+                .map(ModFile::getModInfos)
+                .flatMap(Collection::stream)
+                .collect(groupingBy(IModInfo::getModId));
+
+        // Transform to the full lib id list
+        final Map<String, List<ModFile>> versionedLibIds = uniqueLibListWithVersion.stream()
+                .map(UniqueModListBuilder::getModId)
+                .collect(Collectors.toMap(
+                    Function.identity(),
+                    libFilesWithVersionByModuleName::get
+                ));
+
+        // Its theoretically possible that some mod has somehow moved an id to a secondary place, thus causing a dupe.
+        // We can't handle this
+        final List<String> dupedModErrors = modIds.values().stream()
+                .filter(modInfos -> modInfos.size() > 1)
+                .map(mods -> String.format("\tMod ID: '%s' from mod files: %s",
+                        mods.get(0).getModId(),
+                        mods.stream()
+                                .map(modInfo -> modInfo.getOwningFile().getFile().getFileName()).collect(joining(", "))
+                )).toList();
+
+        if (!dupedModErrors.isEmpty()) {
+            LOGGER.error(LOADING, "Found duplicate mods:\n{}", dupedModErrors.stream().collect(joining("\n")));
+            throw new EarlyLoadingException("Duplicate mods found", null, dupedModErrors.stream()
+                    .map(s -> new EarlyLoadingException.ExceptionData(s))
+                    .toList());
+        }
+
+
+        final List<String> dupedLibErrors = versionedLibIds.values().stream()
+                .filter(modFiles -> modFiles.size() > 1)
+                .map(mods -> String.format("\tLibrary: '%s' from files: %s",
+                        getModId(mods.get(0)),
+                        mods.stream()
+                                .map(modFile -> modFile.getFileName()).collect(joining(", "))
+                )).toList();
+
+        if (!dupedLibErrors.isEmpty()) {
+            LOGGER.error(LOADING, "Found duplicate plugins or libraries:\n{}", dupedLibErrors.stream().collect(joining("\n")));
+            throw new EarlyLoadingException("Duplicate plugins or libraries found", null, dupedLibErrors.stream()
+                    .map(s -> new EarlyLoadingException.ExceptionData(s))
+                    .toList());
+        }
+
+        // Collect unique mod files by module name. This will be used for deduping purposes
+        final Map<String, List<ModFile>> uniqueModFilesByFirstId = uniqueModList.stream()
+                .collect(groupingBy(UniqueModListBuilder::getModId));
+
+        final List<ModFile> loadedList = new ArrayList<>();
+        loadedList.addAll(uniqueModList);
+        loadedList.addAll(uniqueLibListWithVersion);
+
+        return new UniqueModListData(loadedList, uniqueModFilesByFirstId);
+    }
+
+    private ModFile selectNewestModInfo(Map.Entry<String, List<ModFile>> fullList) {
+        List<ModFile> modInfoList = fullList.getValue();
+        if (modInfoList.size() > 1) {
+            LOGGER.debug("Found {} mods for first modid {}, selecting most recent based on version data", modInfoList.size(), fullList.getKey());
+            modInfoList.sort(Comparator.comparing(this::getVersion).reversed());
+            LOGGER.debug("Selected file {} for modid {} with version {}", modInfoList.get(0).getFileName(), fullList.getKey(), this.getVersion(modInfoList.get(0)));
+        }
+        return modInfoList.get(0);
+    }
+
+    private ArtifactVersion getVersion(final ModFile mf)
+    {
+        if (mf.getModFileInfo() == null || mf.getModInfos() == null || mf.getModInfos().isEmpty()) {
+            return mf.getJarVersion();
+        }
+
+        return mf.getModInfos().get(0).getVersion();
+    }
+
+    private static String getModId(ModFile modFile) {
+        if (modFile.getModFileInfo() == null || modFile.getModFileInfo().getMods().isEmpty()) {
+            return modFile.getSecureJar().name();
+        }
+
+        return modFile.getModFileInfo().moduleName();
+    }
+
+    public record UniqueModListData(List<ModFile> modFiles, Map<String, List<ModFile>> modFilesByFirstId) {}
+
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/VersionSupportMatrix.java

@@ -5,6 +5,7 @@
 
 package net.minecraftforge.fml.loading;
 
+import net.minecraftforge.forgespi.language.MavenVersionAdapter;
 import org.apache.maven.artifact.versioning.ArtifactVersion;
 import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
 import org.apache.maven.artifact.versioning.VersionRange;
@@ -18,16 +19,12 @@ public class VersionSupportMatrix {
     private static final HashMap<String, List<ArtifactVersion>> overrideVersions = new HashMap<>();
     static {
         final ArtifactVersion version = new DefaultArtifactVersion(FMLLoader.versionInfo().mcVersion());
-        // if (MavenVersionAdapter.createFromVersionSpec("[1.16.4,1.16.5]").containsVersion(version)) {
-        //     // 1.16.4 is Compatible with 1.16.3
-        //     add("languageloader.javafml", "34");
-        //     add("mod.minecraft",          "1.16.3");
-        //     add("mod.forge",              "34.1.42");
-        //     // 1.16.5 is Compatible with 1.16.4, and thus 1.16.3
-        //     add("languageloader.javafml", "35");
-        //     add("mod.minecraft",          "1.16.4");
-        //     add("mod.forge",              "35.1.37");
-        // }
+         if (MavenVersionAdapter.createFromVersionSpec("[1.19.2]").containsVersion(version)) {
+             // 1.19.2 is Compatible with 1.19.1
+             add("languageloader.javafml", "42");
+             add("mod.minecraft",          "1.19.1");
+             add("mod.forge",              "42.0.9");
+        }
     }
     private static void add(String key, String value) {
         overrideVersions.computeIfAbsent(key, k -> new ArrayList<>()).add(new DefaultArtifactVersion(value));

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractJarFileDependencyLocator.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading.moddiscovery;
+
+import com.mojang.logging.LogUtils;
+import net.minecraftforge.forgespi.locating.IDependencyLocator;
+import net.minecraftforge.forgespi.locating.IModFile;
+import net.minecraftforge.forgespi.locating.ModFileLoadingException;
+import org.slf4j.Logger;
+
+import java.io.FileNotFoundException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Optional;
+
+public abstract class AbstractJarFileDependencyLocator extends AbstractJarFileModProvider implements IDependencyLocator
+{
+    private static final Logger LOGGER = LogUtils.getLogger();
+
+    protected Optional<InputStream> loadResourceFromModFile(final IModFile modFile, final Path path) {
+        try {
+            return Optional.of(Files.newInputStream(modFile.findResource(path.toString())));
+        }
+        catch (final FileNotFoundException e) {
+            LOGGER.debug("Failed to load resource {} from {}, it does not contain dependency information.", path, modFile.getFileName());
+            return Optional.empty();
+        }
+        catch (final Exception e) {
+            LOGGER.error("Failed to load resource {} from mod {}, cause {}", path, modFile.getFileName(), e);
+            return Optional.empty();
+        }
+    }
+
+    protected Optional<IModFile> loadModFileFrom(final IModFile file, final Path path) {
+        try {
+            final Path pathInModFile = file.findResource(path.toString());
+            return Optional.of(createMod(pathInModFile).file());
+        }
+        catch (Exception e) {
+            LOGGER.error("Failed to load mod file {} from {}", path, file.getFileName());
+            throw new ModFileLoadingException("Failed to load mod file "+file.getFileName());
+        }
+    }
+
+    protected String identifyMod(final IModFile modFile) {
+        return modFile.getFileName();
+    }
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractJarFileModLocator.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading.moddiscovery;
+
+import net.minecraftforge.forgespi.locating.IModLocator;
+
+import java.nio.file.Path;
+import java.util.List;
+import java.util.stream.Stream;
+
+public abstract class AbstractJarFileModLocator extends AbstractJarFileModProvider implements IModLocator
+{
+    @Override
+    public List<IModLocator.ModFileOrException> scanMods()
+    {
+        return scanCandidates().map(this::createMod).toList();
+    }
+
+    public abstract Stream<Path> scanCandidates();
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractJarFileModProvider.java

@@ -5,32 +5,22 @@
 
 package net.minecraftforge.fml.loading.moddiscovery;
 
+import com.mojang.logging.LogUtils;
 import cpw.mods.jarhandling.SecureJar;
-import cpw.mods.jarhandling.JarMetadata;
 import net.minecraftforge.fml.loading.LogMarkers;
-import net.minecraftforge.forgespi.language.IConfigurable;
-import net.minecraftforge.forgespi.language.IModFileInfo;
-import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.forgespi.locating.IModFile;
-import net.minecraftforge.forgespi.locating.IModLocator;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.function.Function;
-import java.util.jar.Manifest;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-public abstract class AbstractJarFileLocator extends AbstractModLocator {
-    private static final Logger LOGGER = LogManager.getLogger();
+public abstract class AbstractJarFileModProvider extends AbstractModProvider
+{
+    private static final Logger LOGGER = LogUtils.getLogger();
 
     @Override
     public void scanFile(final IModFile file, final Consumer<Path> pathConsumer) {
@@ -43,15 +33,4 @@ public abstract class AbstractJarFileLocator extends AbstractModLocator {
         }
         LOGGER.debug(LogMarkers.SCAN,"Scan finished: {}", file);
     }
-
-    @Override
-    public List<IModFile> scanMods() {
-        return scanCandidates()
-                .map(this::createMod)
-                .filter(Optional::isPresent)
-                .map(Optional::get)
-                .collect(Collectors.toList());
-    }
-
-    public abstract Stream<Path> scanCandidates();
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractModLocator.java

@@ -1,96 +0,0 @@
-/*
- * Copyright (c) Forge Development LLC and contributors
- * SPDX-License-Identifier: LGPL-2.1-only
- */
-
-package net.minecraftforge.fml.loading.moddiscovery;
-
-import cpw.mods.jarhandling.JarMetadata;
-import cpw.mods.jarhandling.SecureJar;
-import net.minecraftforge.fml.loading.LogMarkers;
-import net.minecraftforge.forgespi.language.IConfigurable;
-import net.minecraftforge.forgespi.language.IModFileInfo;
-import net.minecraftforge.forgespi.language.IModInfo;
-import net.minecraftforge.forgespi.locating.IModFile;
-import net.minecraftforge.forgespi.locating.IModLocator;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-
-import java.nio.file.Path;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.function.Function;
-import java.util.jar.Manifest;
-
-public abstract class AbstractModLocator implements IModLocator {
-    private static final Logger LOGGER = LogManager.getLogger();
-    protected static final String MODS_TOML = "META-INF/mods.toml";
-    protected static final String MANIFEST = "META-INF/MANIFEST.MF";
-
-    protected Optional<IModFile> createMod(Path... path) {
-        var mjm = new ModJarMetadata();
-        var sj = SecureJar.from(
-                Manifest::new,
-                jar -> jar.findFile(MODS_TOML).isPresent() ? mjm : JarMetadata.from(jar, path),
-                (root, p) -> true,
-                path
-        );
-
-        IModFile mod;
-        var type = sj.getManifest().getMainAttributes().getValue(ModFile.TYPE);
-        if (sj.findFile(MODS_TOML).isPresent()) {
-            LOGGER.debug(LogMarkers.SCAN, "Found {} mod of type {}: {}", MODS_TOML, type, path);
-            mod = new ModFile(sj, this, ModFileParser::modsTomlParser);
-        } else if (type != null) {
-            LOGGER.debug(LogMarkers.SCAN, "Found {} mod of type {}: {}", MANIFEST, type, path);
-            mod = new ModFile(sj, this, this::manifestParser);
-        } else {
-            return Optional.empty();
-        }
-
-        mjm.setModFile(mod);
-        return Optional.of(mod);
-    }
-
-    protected IModFileInfo manifestParser(final IModFile mod) {
-        Function<String, Optional<String>> cfg = name -> Optional.ofNullable(mod.getSecureJar().getManifest().getMainAttributes().getValue(name));
-        var license = cfg.apply("LICENSE").orElse("");
-        var dummy = new IConfigurable() {
-            @Override
-            public <T> Optional<T> getConfigElement(String... key) {
-                return Optional.empty();
-            }
-            @Override
-            public List<? extends IConfigurable> getConfigList(String... key) {
-                return Collections.emptyList();
-            }
-        };
-
-        return new IModFileInfo() {
-            @Override public List<IModInfo> getMods() { return Collections.emptyList(); }
-            @Override public List<LanguageSpec> requiredLanguageLoaders() { return Collections.emptyList(); }
-            @Override public boolean showAsResourcePack() { return false; }
-            @Override public Map<String, Object> getFileProperties() { return Collections.emptyMap(); }
-            @Override public String getLicense() { return license; }
-            @Override public IModFile getFile() { return mod; }
-            @Override public IConfigurable getConfig() { return dummy; }
-
-            // These Should never be called as it's only called from ModJarMetadata.version and we bypass that
-            @Override public String moduleName() { return mod.getSecureJar().name(); }
-            @Override public String versionString() { return null; }
-            @Override public List<String> usesServices() { return null; }
-
-            @Override
-            public String toString() {
-                return "IModFileInfo(" + mod.getFilePath() + ")";
-            }
-        };
-    }
-
-    @Override
-    public boolean isValid(final IModFile modFile) {
-        return true;
-    }
-}

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractModProvider.java

@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading.moddiscovery;
+
+import com.mojang.logging.LogUtils;
+import cpw.mods.jarhandling.JarMetadata;
+import cpw.mods.jarhandling.SecureJar;
+import net.minecraftforge.fml.loading.LogMarkers;
+import net.minecraftforge.forgespi.language.IConfigurable;
+import net.minecraftforge.forgespi.language.IModFileInfo;
+import net.minecraftforge.forgespi.language.IModInfo;
+import net.minecraftforge.forgespi.locating.IModFile;
+import net.minecraftforge.forgespi.locating.IModLocator;
+import net.minecraftforge.forgespi.locating.IModProvider;
+import net.minecraftforge.forgespi.locating.ModFileLoadingException;
+import org.slf4j.Logger;
+
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.jar.Manifest;
+
+public abstract class AbstractModProvider implements IModProvider
+{
+    private static final   Logger LOGGER    = LogUtils.getLogger();
+    protected static final String MODS_TOML = "META-INF/mods.toml";
+    protected static final String MANIFEST = "META-INF/MANIFEST.MF";
+
+    protected IModLocator.ModFileOrException createMod(Path... path) {
+        return this.createMod(getDefaultJarModType(), path);
+    }
+
+    // FORGE: Backporting artifact, the defaultType must be the first parameter since path is varargs
+    protected IModLocator.ModFileOrException createMod(String defaultType, Path... path) {
+        var mjm = new ModJarMetadata();
+        var sj = SecureJar.from(
+                Manifest::new,
+                jar -> jar.moduleDataProvider().findFile(MODS_TOML).isPresent() ? mjm : JarMetadata.from(jar, path),
+                null,
+                path
+        );
+
+        IModFile mod;
+        var type = sj.moduleDataProvider().getManifest().getMainAttributes().getValue(ModFile.TYPE);
+        if (type == null) {
+            type = defaultType;
+        }
+        if (sj.moduleDataProvider().findFile(MODS_TOML).isPresent()) {
+            LOGGER.debug(LogMarkers.SCAN, "Found {} mod of type {}: {}", MODS_TOML, type, path);
+            mod = new ModFile(sj, this, ModFileParser::modsTomlParser);
+        } else if (type != null) {
+            LOGGER.debug(LogMarkers.SCAN, "Found {} mod of type {}: {}", MANIFEST, type, path);
+            mod = new ModFile(sj, this, this::manifestParser, type);
+        } else {
+            return new IModLocator.ModFileOrException(null, new ModFileLoadingException("Invalid mod file found "+ Arrays.toString(path)));
+        }
+
+        mjm.setModFile(mod);
+        return new IModLocator.ModFileOrException(mod, null);
+    }
+
+    protected IModFileInfo manifestParser(final IModFile mod) {
+        Function<String, Optional<String>> cfg = name -> Optional.ofNullable(mod.getSecureJar().moduleDataProvider().getManifest().getMainAttributes().getValue(name));
+        var license = cfg.apply("LICENSE").orElse("");
+        var dummy = new IConfigurable() {
+            @Override
+            public <T> Optional<T> getConfigElement(String... key) {
+                return Optional.empty();
+            }
+            @Override
+            public List<? extends IConfigurable> getConfigList(String... key) {
+                return Collections.emptyList();
+            }
+        };
+
+        return new DefaultModFileInfo(mod, license, dummy);
+    }
+
+    @Override
+    public boolean isValid(final IModFile modFile) {
+        return true;
+    }
+
+    protected String getDefaultJarModType() {
+        return null;
+    }
+
+    private record DefaultModFileInfo(IModFile mod, String license, IConfigurable configurable) implements IModFileInfo, IConfigurable {
+        @Override
+        public <T> Optional<T> getConfigElement(final String... strings)
+        {
+            return Optional.empty();
+        }
+
+        @Override
+        public List<? extends IConfigurable> getConfigList(final String... strings)
+        {
+            return null;
+        }
+
+        @Override public List<IModInfo> getMods() { return Collections.emptyList(); }
+        @Override public List<LanguageSpec> requiredLanguageLoaders() { return Collections.emptyList(); }
+        @Override public boolean showAsResourcePack() { return false; }
+        @Override public Map<String, Object> getFileProperties() { return Collections.emptyMap(); }
+        @Override
+        public String getLicense() { return license; }
+
+        @Override public IModFile getFile() { return mod; }
+        @Override public IConfigurable getConfig() { return configurable; }
+
+        // These Should never be called as it's only called from ModJarMetadata.version and we bypass that
+        @Override public String moduleName() { return mod.getSecureJar().name(); }
+        @Override public String versionString() { return null; }
+        @Override public List<String> usesServices() { return null; }
+
+        @Override
+        public String toString() {
+            return "IModFileInfo(" + mod.getFilePath() + ")";
+        }
+    }
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/BackgroundScanHandler.java

@@ -5,11 +5,11 @@
 
 package net.minecraftforge.fml.loading.moddiscovery;
 
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.LoadingModList;
 import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.forgespi.language.ModFileScanData;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.time.Duration;
 import java.time.Instant;
@@ -28,7 +28,7 @@ public class BackgroundScanHandler
         ERRORED
     }
 
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private final ExecutorService modContentScanner;
     private final List<ModFile> pendingFiles;
     private final List<ModFile> scannedFiles;

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ClasspathLocator.java

@@ -5,9 +5,10 @@
 
 package net.minecraftforge.fml.loading.moddiscovery;
 
+import net.minecraftforge.fml.loading.ClasspathLocatorUtils;
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.LogMarkers;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.File;
 import java.io.IOException;
@@ -24,8 +25,9 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Stream;
 
-public class ClasspathLocator extends AbstractJarFileLocator {
-    private static final Logger LOGGER = LogManager.getLogger();
+public class ClasspathLocator extends AbstractJarFileModLocator
+{
+    private static final Logger LOGGER = LogUtils.getLogger();
     private final List<Path> legacyClasspath = Arrays.stream(System.getProperty("legacyClassPath", "").split(File.pathSeparator)).map(Path::of).toList();
     private boolean enabled = false;
 
@@ -48,7 +50,7 @@ public class ClasspathLocator extends AbstractJarFileLocator {
 
             return paths.build();
         } catch (IOException e) {
-            LOGGER.fatal(LogMarkers.SCAN, "Error trying to find resources", e);
+            LOGGER.error(LogMarkers.SCAN, "Error trying to find resources", e);
             throw new RuntimeException(e);
         }
     }
@@ -58,7 +60,7 @@ public class ClasspathLocator extends AbstractJarFileLocator {
         final Enumeration<URL> resources = ClassLoader.getSystemClassLoader().getResources(resource);
         while (resources.hasMoreElements()) {
             URL url = resources.nextElement();
-            Path path = findJarPathFor(resource, resource, url);
+            Path path = ClasspathLocatorUtils.findJarPathFor(resource, resource, url);
             if (claimed.stream().anyMatch(path::equals) || !Files.exists(path) || Files.isDirectory(path))
                 continue;
             ret.add(path);
@@ -85,7 +87,7 @@ public class ClasspathLocator extends AbstractJarFileLocator {
             //LOGGER.debug(CORE, "Found JAR {} at path {}", jarName, path.toString());
             return path;
         } catch (NullPointerException | URISyntaxException e) {
-            LOGGER.fatal(LogMarkers.SCAN, "Failed to find JAR for class {} - {}", resourceName, jarName);
+            LOGGER.error(LogMarkers.SCAN, "Failed to find JAR for class {} - {}", resourceName, jarName);
             throw new RuntimeException("Unable to locate "+resourceName+" - "+jarName, e);
         }
     }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ExplodedDirectoryLocator.java

@@ -5,11 +5,11 @@
 
 package net.minecraftforge.fml.loading.moddiscovery;
 
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.forgespi.locating.IModFile;
 import net.minecraftforge.forgespi.locating.IModLocator;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -22,7 +22,7 @@ import java.util.function.Consumer;
 import java.util.stream.Stream;
 
 public class ExplodedDirectoryLocator implements IModLocator {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
 
     public record ExplodedMod(String modid, List<Path> paths) {}
 
@@ -30,14 +30,14 @@ public class ExplodedDirectoryLocator implements IModLocator {
     private final Map<ExplodedMod, IModFile> mods = new HashMap<>();
 
     @Override
-    public List<IModFile> scanMods() {
+    public List<IModLocator.ModFileOrException> scanMods() {
         explodedMods.forEach(explodedMod ->
                 ModJarMetadata.buildFile(this,
-                        jar->jar.findFile("/META-INF/mods.toml").isPresent(),
-                        (a,b) -> true,
+                        jar->jar.moduleDataProvider().findFile("/META-INF/mods.toml").isPresent(),
+                        null,
                         explodedMod.paths().toArray(Path[]::new))
                 .ifPresentOrElse(f->mods.put(explodedMod, f), () -> LOGGER.warn(LogMarkers.LOADING, "Failed to find exploded resource mods.toml in directory {}", explodedMod.paths().get(0).toString())));
-        return List.copyOf(mods.values());
+        return mods.values().stream().map(mf->new IModLocator.ModFileOrException(mf, null)).toList();
     }
 
     @Override

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/InvalidModFileException.java

@@ -6,16 +6,22 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import net.minecraftforge.forgespi.language.IModFileInfo;
+import net.minecraftforge.forgespi.locating.ModFileLoadingException;
 
 import java.util.Locale;
+import java.util.Optional;
 
-public class InvalidModFileException extends RuntimeException
+public class InvalidModFileException extends ModFileLoadingException
 {
     private final IModFileInfo modFileInfo;
 
     public InvalidModFileException(String message, IModFileInfo modFileInfo)
     {
-        super(String.format(Locale.ENGLISH, "%s (%s)", message, ((ModFileInfo)modFileInfo).getFile().getFileName()));
+        super(String.format(Locale.ROOT, "%s (%s)", message, Optional.ofNullable(modFileInfo).map(mf->mf.getFile().getFileName()).orElse("MISSING FILE NAME")));
         this.modFileInfo = modFileInfo;
     }
+
+    public IModFileInfo getBrokenFile() {
+        return modFileInfo;
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/JarInJarDependencyLocator.java

@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml.loading.moddiscovery;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import com.mojang.logging.LogUtils;
+import net.minecraftforge.fml.loading.EarlyLoadingException;
+import net.minecraftforge.forgespi.language.IModInfo;
+import net.minecraftforge.forgespi.locating.IModFile;
+import net.minecraftforge.forgespi.locating.ModFileLoadingException;
+import net.minecraftforge.jarjar.selection.JarSelector;
+import org.apache.maven.artifact.versioning.ArtifactVersion;
+import org.apache.maven.artifact.versioning.VersionRange;
+import org.jetbrains.annotations.NotNull;
+import org.slf4j.Logger;
+
+import java.net.URI;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class JarInJarDependencyLocator extends AbstractJarFileDependencyLocator
+{
+    private static final Logger LOGGER = LogUtils.getLogger();
+
+    @Override
+    public String name()
+    {
+        return "JarInJar";
+    }
+
+    @Override
+    public List<IModFile> scanMods(final Iterable<IModFile> loadedMods)
+    {
+        final List<IModFile> sources = Lists.newArrayList();
+        loadedMods.forEach(sources::add);
+
+        final List<IModFile> dependenciesToLoad = JarSelector.detectAndSelect(sources, this::loadResourceFromModFile, this::loadModFileFrom, this::identifyMod, this::exception);
+
+        if (dependenciesToLoad.isEmpty())
+        {
+            LOGGER.info("No dependencies to load found. Skipping!");
+            return Collections.emptyList();
+        }
+
+        LOGGER.info("Found {} dependencies adding them to mods collection", dependenciesToLoad.size());
+        return dependenciesToLoad;
+    }
+
+    @Override
+    public void initArguments(final Map<String, ?> arguments)
+    {
+        // NO-OP, for now
+    }
+
+    @Override
+    protected String getDefaultJarModType()
+    {
+        return IModFile.Type.GAMELIBRARY.name();
+    }
+
+    @SuppressWarnings("resource")
+    @Override
+    protected Optional<IModFile> loadModFileFrom(final IModFile file, final Path path)
+    {
+        try
+        {
+            final Path pathInModFile = file.findResource(path.toString());
+            final URI filePathUri = new URI("jij:" + (pathInModFile.toAbsolutePath().toUri().getRawSchemeSpecificPart())).normalize();
+            final Map<String, ?> outerFsArgs = ImmutableMap.of("packagePath", pathInModFile);
+            final FileSystem zipFS = FileSystems.newFileSystem(filePathUri, outerFsArgs);
+            final Path pathInFS = zipFS.getPath("/");
+            final IModFile.Type parentType = file.getType();
+            final String modType;
+            if (parentType == IModFile.Type.LIBRARY || parentType == IModFile.Type.LANGPROVIDER) {
+                modType = IModFile.Type.LIBRARY.name();
+            } else {
+                modType = IModFile.Type.GAMELIBRARY.name();
+            }
+            return Optional.of(createMod(modType, pathInFS).file());
+        }
+        catch (Exception e)
+        {
+            LOGGER.error("Failed to load mod file {} from {}", path, file.getFileName());
+            final RuntimeException exception = new ModFileLoadingException("Failed to load mod file " + file.getFileName());
+            exception.initCause(e);
+
+            throw exception;
+        }
+    }
+
+    protected EarlyLoadingException exception(Collection<JarSelector.ResolutionFailureInformation<IModFile>> failedDependencies)
+    {
+
+        final List<EarlyLoadingException.ExceptionData> errors = failedDependencies.stream()
+               .filter(entry -> !entry.sources().isEmpty()) //Should never be the case, but just to be sure
+               .map(this::buildExceptionData)
+               .toList();
+
+        return new EarlyLoadingException(failedDependencies.size() + " Dependency restrictions were not met.", null, errors);
+    }
+
+    @NotNull
+    private EarlyLoadingException.ExceptionData buildExceptionData(final JarSelector.ResolutionFailureInformation<IModFile> entry)
+    {
+        return new EarlyLoadingException.ExceptionData(
+                getErrorTranslationKey(entry),
+                entry.identifier().group() + ":" + entry.identifier().artifact(),
+                entry.sources()
+                     .stream()
+                     .flatMap(this::getModWithVersionRangeStream)
+                     .map(this::formatError)
+                     .collect(Collectors.joining(", "))
+        );
+    }
+
+    @NotNull
+    private String getErrorTranslationKey(final JarSelector.ResolutionFailureInformation<IModFile> entry)
+    {
+        return entry.failureReason() == JarSelector.FailureReason.VERSION_RESOLUTION_FAILED ?
+                       "fml.dependencyloading.conflictingdependencies" :
+                       "fml.dependencyloading.mismatchedcontaineddependencies";
+    }
+
+    @NotNull
+    private Stream<ModWithVersionRange> getModWithVersionRangeStream(final JarSelector.SourceWithRequestedVersionRange<IModFile> file)
+    {
+        return file.sources()
+                   .stream()
+                   .map(IModFile::getModFileInfo)
+                   .flatMap(modFileInfo -> modFileInfo.getMods().stream())
+                   .map(modInfo -> new ModWithVersionRange(modInfo, file.requestedVersionRange(), file.includedVersion()));
+    }
+
+    @NotNull
+    private String formatError(final ModWithVersionRange modWithVersionRange)
+    {
+        return "\u00a7e" + modWithVersionRange.modInfo().getModId() + "\u00a7r - \u00a74" + modWithVersionRange.versionRange().toString() + "\u00a74 - \u00a72" + modWithVersionRange.artifactVersion().toString() + "\u00a72";
+    }
+
+    @Override
+    protected String identifyMod(final IModFile modFile)
+    {
+        if (modFile.getModFileInfo() == null || modFile.getModInfos().isEmpty())
+        {
+            return modFile.getFileName();
+        }
+
+        return modFile.getModInfos().stream().map(IModInfo::getModId).collect(Collectors.joining());
+    }
+
+    private record ModWithVersionRange(IModInfo modInfo, VersionRange versionRange, ArtifactVersion artifactVersion)
+    {}
+}

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/MavenDirectoryLocator.java

@@ -15,7 +15,8 @@ import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-public class MavenDirectoryLocator extends AbstractJarFileLocator {
+public class MavenDirectoryLocator extends AbstractJarFileModLocator
+{
     private List<Path> modCoords;
 
     @Override

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/MinecraftLocator.java

@@ -6,6 +6,7 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.electronwill.nightconfig.core.Config;
+import com.mojang.logging.LogUtils;
 import cpw.mods.jarhandling.SecureJar;
 import net.minecraftforge.fml.loading.FMLLoader;
 import net.minecraftforge.fml.loading.LogMarkers;
@@ -13,21 +14,24 @@ import net.minecraftforge.forgespi.language.IModFileInfo;
 import net.minecraftforge.forgespi.locating.IModFile;
 import net.minecraftforge.forgespi.locating.IModLocator;
 import net.minecraftforge.forgespi.locating.ModFileFactory;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.IOException;
-import java.nio.file.*;
-import java.util.*;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-public class MinecraftLocator extends AbstractModLocator {
-    private static final Logger LOGGER = LogManager.getLogger();
+public class MinecraftLocator extends AbstractModProvider implements IModLocator
+{
+    private static final Logger LOGGER = LogUtils.getLogger();
 
     @Override
-    public List<IModFile> scanMods() {
+    public List<IModLocator.ModFileOrException> scanMods() {
         final var launchHandler = FMLLoader.getLaunchHandler();
         var baseMC = launchHandler.getMinecraftPaths();
         var mcjar = ModJarMetadata.buildFile(j->ModFileFactory.FACTORY.build(j, this, this::buildMinecraftTOML), j->true, baseMC.minecraftFilter(), baseMC.minecraftPaths().toArray(Path[]::new)).orElseThrow();
@@ -36,12 +40,11 @@ public class MinecraftLocator extends AbstractModLocator {
                 .map(sj -> new ModFile(sj, this, ModFileParser::modsTomlParser))
                 .collect(Collectors.<IModFile>toList());
         var othermods = baseMC.otherModPaths().stream()
-                .map(p -> createMod(p.toArray(Path[]::new)).orElse(null))
-                .filter(Objects::nonNull)
-                .toList();
+                .map(p -> createMod(p.toArray(Path[]::new)))
+                .filter(Objects::nonNull);
         artifacts.add(mcjar);
-        artifacts.addAll(othermods);
-        return artifacts;
+
+        return Stream.concat(artifacts.stream().map(f -> new ModFileOrException(f, null)), othermods).toList();
     }
 
     private IModFileInfo buildMinecraftTOML(final IModFile iModFile) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModDiscoverer.java

@@ -5,62 +5,190 @@
 
 package net.minecraftforge.fml.loading.moddiscovery;
 
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Maps;
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.Launcher;
 import cpw.mods.modlauncher.api.IModuleLayerManager;
 import cpw.mods.modlauncher.util.ServiceLoaderUtils;
+import net.minecraftforge.fml.loading.EarlyLoadingException;
+import net.minecraftforge.fml.loading.FMLLoader;
 import net.minecraftforge.fml.loading.LogMarkers;
+import net.minecraftforge.fml.loading.UniqueModListBuilder;
 import net.minecraftforge.fml.loading.progress.StartupMessageManager;
 import net.minecraftforge.forgespi.Environment;
+import net.minecraftforge.forgespi.language.IModFileInfo;
+import net.minecraftforge.forgespi.locating.IDependencyLocator;
 import net.minecraftforge.forgespi.locating.IModFile;
 import net.minecraftforge.forgespi.locating.IModLocator;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+import org.slf4j.Logger;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.ServiceLoader;
 import java.util.stream.Collectors;
 
 public class ModDiscoverer {
-    private static final Logger LOGGER = LogManager.getLogger();
-    private final ServiceLoader<IModLocator> locators;
-    private final List<IModLocator> locatorList;
+    private static final Logger LOGGER = LogUtils.getLogger();
+    private final ServiceLoader<IModLocator> modLocators;
+    private final ServiceLoader<IDependencyLocator> dependencyLocators;
+    private final List<IModLocator>          modLocatorList;
+    private final List<IDependencyLocator>   dependencyLocatorList;
 
     public ModDiscoverer(Map<String, ?> arguments) {
         Launcher.INSTANCE.environment().computePropertyIfAbsent(Environment.Keys.MODDIRECTORYFACTORY.get(), v->ModsFolderLocator::new);
         Launcher.INSTANCE.environment().computePropertyIfAbsent(Environment.Keys.PROGRESSMESSAGE.get(), v-> StartupMessageManager.locatorConsumer().orElseGet(()-> s->{}));
         final var moduleLayerManager = Launcher.INSTANCE.environment().findModuleLayerManager().orElseThrow();
-        locators = ServiceLoader.load(moduleLayerManager.getLayer(IModuleLayerManager.Layer.SERVICE).orElseThrow(), IModLocator.class);
-        locatorList = ServiceLoaderUtils.streamServiceLoader(()->locators, sce->LOGGER.error("Failed to load locator list", sce)).collect(Collectors.toList());
-        locatorList.forEach(l->l.initArguments(arguments));
-        LOGGER.debug(LogMarkers.CORE,"Found Mod Locators : {}", ()->locatorList.stream().map(iModLocator -> "("+iModLocator.name() + ":" + iModLocator.getClass().getPackage().getImplementationVersion()+")").collect(Collectors.joining(",")));
-    }
-
-    ModDiscoverer(List<IModLocator> locatorList) {
-        this.locatorList = locatorList;
-        this.locators = null;
+        modLocators = ServiceLoader.load(moduleLayerManager.getLayer(IModuleLayerManager.Layer.SERVICE).orElseThrow(), IModLocator.class);
+        dependencyLocators = ServiceLoader.load(moduleLayerManager.getLayer(IModuleLayerManager.Layer.SERVICE).orElseThrow(), IDependencyLocator.class);
+        modLocatorList = ServiceLoaderUtils.streamServiceLoader(()-> modLocators, sce->LOGGER.error("Failed to load mod locator list", sce)).collect(Collectors.toList());
+        modLocatorList.forEach(l->l.initArguments(arguments));
+        dependencyLocatorList = ServiceLoaderUtils.streamServiceLoader(()-> dependencyLocators, sce->LOGGER.error("Failed to load dependency locator list", sce)).collect(Collectors.toList());
+        dependencyLocatorList.forEach(l->l.initArguments(arguments));
+        if (LOGGER.isDebugEnabled(LogMarkers.CORE))
+        {
+            LOGGER.debug(LogMarkers.CORE, "Found Mod Locators : {}", modLocatorList.stream()
+                                                                       .map(modLocator -> "(%s:%s)".formatted(modLocator.name(),
+                                                                         modLocator.getClass().getPackage().getImplementationVersion())).collect(Collectors.joining(",")));
+        }
+        if (LOGGER.isDebugEnabled(LogMarkers.CORE))
+        {
+            LOGGER.debug(LogMarkers.CORE, "Found Dependency Locators : {}", dependencyLocatorList.stream()
+                                                                       .map(dependencyLocator -> "(%s:%s)".formatted(dependencyLocator.name(),
+                                                                         dependencyLocator.getClass().getPackage().getImplementationVersion())).collect(Collectors.joining(",")));
+        }
     }
 
     public ModValidator discoverMods() {
-        LOGGER.debug(LogMarkers.SCAN,"Scanning for mods and other resources to load. We know {} ways to find mods", locatorList.size());
-        var loadedFiles = new ArrayList<>();
-        for (IModLocator locator : locatorList) {
-            LOGGER.debug(LogMarkers.SCAN,"Trying locator {}", locator);
-            var modFiles = locator.scanMods();
-            for (IModFile mf : modFiles) {
-                LOGGER.info(LogMarkers.SCAN, "Found mod file {} of type {} with locator {}", mf.getFileName(), mf.getType(), mf.getLocator());
-                StartupMessageManager.modLoaderConsumer().ifPresent(c->c.accept("Found mod file "+mf.getFileName()+" of type "+mf.getType()));
-            }
-            loadedFiles.addAll(modFiles);
-        }
-        final var modFilesMap = loadedFiles.stream()
-                .map(ModFile.class::cast)
-                .collect(Collectors.groupingBy(IModFile::getType));
+        LOGGER.debug(LogMarkers.SCAN,"Scanning for mods and other resources to load. We know {} ways to find mods", modLocatorList.size());
+        List<ModFile> loadedFiles = new ArrayList<>();
+        List<EarlyLoadingException.ExceptionData> discoveryErrorData = new ArrayList<>();
+        boolean successfullyLoadedMods = true;
+        List<IModFileInfo> brokenFiles = new ArrayList<>();
 
-        var validator = new ModValidator(modFilesMap);
+        boolean distIsDedicatedServer = FMLLoader.getDist().isDedicatedServer();
+        //Loop all mod locators to get the prime mods to load from.
+        for (IModLocator locator : modLocatorList) {
+            try {
+                LOGGER.debug(LogMarkers.SCAN, "Trying locator {}", locator);
+                var candidates = locator.scanMods();
+                LOGGER.debug(LogMarkers.SCAN, "Locator {} found {} candidates or errors", locator, candidates.size());
+                var exceptions = candidates.stream().map(IModLocator.ModFileOrException::ex).filter(Objects::nonNull).toList();
+                if (!exceptions.isEmpty()) {
+                    LOGGER.debug(LogMarkers.SCAN, "Locator {} found {} invalid mod files", locator, exceptions.size());
+                    brokenFiles.addAll(exceptions.stream().map(e->e instanceof InvalidModFileException ime ? ime.getBrokenFile() : null).filter(Objects::nonNull).toList());
+                }
+                var locatedFiles = candidates.stream().map(IModLocator.ModFileOrException::file).filter(Objects::nonNull).collect(Collectors.toList());
+
+                var badModFiles = locatedFiles.stream().filter(file -> !(file instanceof ModFile)).toList();
+                if (!badModFiles.isEmpty()) {
+                    LOGGER.error(LogMarkers.SCAN, "Locator {} returned {} files which is are not ModFile instances! They will be skipped!", locator, badModFiles.size());
+                    brokenFiles.addAll(badModFiles.stream().map(IModFile::getModFileInfo).toList());
+                    locatedFiles.removeAll(badModFiles);
+                }
+
+                if (distIsDedicatedServer) {
+                    var clientOnlyModFiles = locatedFiles.stream()
+                            .filter(file -> {
+                                // some mod files can have null infos, like javafml, mclanguage, lowcode, and fmlcore
+                                @Nullable var info = file.getModFileInfo();
+
+                                return info != null && (Boolean) info.getFileProperties().getOrDefault(ModFileInfo.CLIENT_SIDE_ONLY_PROP, Boolean.FALSE);
+                            })
+                            .toList();
+                    if (!clientOnlyModFiles.isEmpty()) {
+                        LOGGER.warn(LogMarkers.SCAN, "Locator {} returned {} files which are client-side-only mods, but we're on a dedicated server. They will be skipped!", locator, clientOnlyModFiles.size());
+                        locatedFiles.removeAll(clientOnlyModFiles);
+                    }
+                }
+
+                LOGGER.debug(LogMarkers.SCAN, "Locator {} found {} valid mod files", locator, locatedFiles.size());
+                handleLocatedFiles(loadedFiles, locatedFiles);
+            } catch (InvalidModFileException imfe) {
+                // We don't generally expect this exception, since it should come from the candidates stream above and be handled in the Locator, but just in case.
+                LOGGER.error(LogMarkers.SCAN, "Locator {} found an invalid mod file {}", locator, imfe.getBrokenFile(), imfe);
+                brokenFiles.add(imfe.getBrokenFile());
+            } catch (EarlyLoadingException exception) {
+                LOGGER.error(LogMarkers.SCAN, "Failed to load mods with locator {}", locator, exception);
+                discoveryErrorData.addAll(exception.getAllData());
+            }
+        }
+
+        //First processing run of the mod list. Any duplicates will cause resolution failure and dependency loading will be skipped.
+        Map<IModFile.Type, List<ModFile>> modFilesMap = Maps.newHashMap();
+        try {
+            final UniqueModListBuilder modsUniqueListBuilder = new UniqueModListBuilder(loadedFiles);
+            final UniqueModListBuilder.UniqueModListData uniqueModsData = modsUniqueListBuilder.buildUniqueList();
+
+            //Grab the temporary results.
+            //This allows loading to continue to a base state, in case dependency loading fails.
+            modFilesMap = uniqueModsData.modFiles().stream()
+                            .collect(Collectors.groupingBy(IModFile::getType));
+            loadedFiles = uniqueModsData.modFiles();
+        }
+        catch (EarlyLoadingException exception) {
+            LOGGER.error(LogMarkers.SCAN, "Failed to build unique mod list after mod discovery.", exception);
+            discoveryErrorData.addAll(exception.getAllData());
+            successfullyLoadedMods = false;
+        }
+
+        //We can continue loading if prime mods loaded successfully.
+        if (successfullyLoadedMods) {
+            LOGGER.debug(LogMarkers.SCAN, "Successfully Loaded {} mods. Attempting to load dependencies...", loadedFiles.size());
+            for (IDependencyLocator locator : dependencyLocatorList) {
+                try {
+                    LOGGER.debug(LogMarkers.SCAN,"Trying locator {}", locator);
+                    final List<IModFile> locatedMods = ImmutableList.copyOf(loadedFiles);
+
+                    var locatedFiles = locator.scanMods(locatedMods);
+                    if (locatedFiles.stream().anyMatch(file -> !(file instanceof ModFile))) {
+                        LOGGER.error(LogMarkers.SCAN, "A dependency locator returned a file which is not a ModFile instance!. They will be skipped!");
+                    }
+
+                    handleLocatedFiles(loadedFiles, locatedFiles);
+                }
+                catch (EarlyLoadingException exception) {
+                    LOGGER.error(LogMarkers.SCAN, "Failed to load dependencies with locator {}", locator, exception);
+                    discoveryErrorData.addAll(exception.getAllData());
+                }
+            }
+
+            //Second processing run of the mod list. Any duplicates will cause resolution failure and only the mods list will be loaded.
+            try {
+                final UniqueModListBuilder modsAndDependenciesUniqueListBuilder = new UniqueModListBuilder(loadedFiles);
+                final UniqueModListBuilder.UniqueModListData uniqueModsAndDependenciesData = modsAndDependenciesUniqueListBuilder.buildUniqueList();
+
+                //We now only need the mod files map, not the list.
+                modFilesMap = uniqueModsAndDependenciesData.modFiles().stream()
+                                .collect(Collectors.groupingBy(IModFile::getType));
+            } catch (EarlyLoadingException exception) {
+                LOGGER.error(LogMarkers.SCAN, "Failed to build unique mod list after dependency discovery.", exception);
+                discoveryErrorData.addAll(exception.getAllData());
+                modFilesMap = loadedFiles.stream().collect(Collectors.groupingBy(IModFile::getType));
+            }
+        }
+        else {
+            //Failure notify the listeners.
+            LOGGER.error(LogMarkers.SCAN, "Mod Discovery failed. Skipping dependency discovery.");
+        }
+
+        //Validate the loading. With a deduplicated list, we can now successfully process the artifacts and load
+        //transformer plugins.
+        var validator = new ModValidator(modFilesMap, brokenFiles, discoveryErrorData);
         validator.stage1Validation();
         return validator;
     }
 
+    private void handleLocatedFiles(final List<ModFile> loadedFiles, final List<IModFile> locatedFiles)
+    {
+        var locatedModFiles = locatedFiles.stream().filter(ModFile.class::isInstance).map(ModFile.class::cast).toList();
+        for (IModFile mf : locatedModFiles) {
+            LOGGER.info(LogMarkers.SCAN, "Found mod file {} of type {} with provider {}", mf.getFileName(), mf.getType(), mf.getProvider());
+            StartupMessageManager.modLoaderConsumer().ifPresent(c->c.accept("Found mod file "+mf.getFileName()+" of type "+mf.getType()));
+        }
+        loadedFiles.addAll(locatedModFiles);
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModFile.java

@@ -6,6 +6,7 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.google.common.collect.ImmutableMap;
+import com.mojang.logging.LogUtils;
 import cpw.mods.jarhandling.SecureJar;
 import net.minecraftforge.fml.loading.FMLLoader;
 import net.minecraftforge.fml.loading.LogMarkers;
@@ -15,10 +16,11 @@ import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.forgespi.language.IModLanguageProvider;
 import net.minecraftforge.forgespi.language.ModFileScanData;
 import net.minecraftforge.forgespi.locating.IModFile;
-import net.minecraftforge.forgespi.locating.IModLocator;
+import net.minecraftforge.forgespi.locating.IModProvider;
 import net.minecraftforge.forgespi.locating.ModFileFactory;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.apache.maven.artifact.versioning.ArtifactVersion;
+import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
+import org.slf4j.Logger;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -37,7 +39,7 @@ public class ModFile implements IModFile {
     // Mods either must have a mods.toml or a manifest. We can no longer just put any jar on the classpath.
     @Deprecated(forRemoval = true, since = "1.18")
     public static final Manifest DEFAULTMANIFEST;
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
 
     static {
         DEFAULTMANIFEST = new Manifest();
@@ -51,9 +53,9 @@ public class ModFile implements IModFile {
     private Throwable scanError;
     private final SecureJar jar;
     private final Type modFileType;
-    private final Manifest manifest;
-    private final IModLocator locator;
-    private IModFileInfo modFileInfo;
+    private final Manifest     manifest;
+    private final IModProvider provider;
+    private       IModFileInfo modFileInfo;
     private ModFileScanData fileModFileScanData;
     private CompletableFuture<ModFileScanData> futureScanResult;
     private List<CoreModFile> coreMods;
@@ -62,15 +64,19 @@ public class ModFile implements IModFile {
     static final Attributes.Name TYPE = new Attributes.Name("FMLModType");
     private SecureJar.Status securityStatus;
 
-    public ModFile(final SecureJar jar, final IModLocator locator, final ModFileFactory.ModFileInfoParser parser) {
-        this.locator = locator;
+    public ModFile(final SecureJar jar, final IModProvider provider, final ModFileFactory.ModFileInfoParser parser) {
+        this(jar, provider, parser, parseType(jar));
+    }
+
+    public ModFile(final SecureJar jar, final IModProvider provider, final ModFileFactory.ModFileInfoParser parser, String type) {
+        this.provider = provider;
         this.jar = jar;
         this.parser = parser;
 
-        manifest = this.jar.getManifest();
-        final Optional<String> value = Optional.ofNullable(manifest.getMainAttributes().getValue(TYPE));
-        modFileType = Type.valueOf(value.orElse("MOD"));
+        manifest = this.jar.moduleDataProvider().getManifest();
+        modFileType = Type.valueOf(type);
         jarVersion = Optional.ofNullable(manifest.getMainAttributes().getValue(Attributes.Name.IMPLEMENTATION_VERSION)).orElse("0.0NONE");
+        this.modFileInfo = ModFileParser.readModList(this, this.parser);
     }
 
     @Override
@@ -123,7 +129,7 @@ public class ModFile implements IModFile {
     }
 
     public void scanFile(Consumer<Path> pathConsumer) {
-        locator.scanFile(this, pathConsumer);
+        provider.scanFile(this, pathConsumer);
     }
 
     public void setFutureScanResult(CompletableFuture<ModFileScanData> future) {
@@ -188,8 +194,8 @@ public class ModFile implements IModFile {
     }
 
     @Override
-    public IModLocator getLocator() {
-        return locator;
+    public IModProvider getProvider() {
+        return provider;
     }
 
     @Override
@@ -201,4 +207,15 @@ public class ModFile implements IModFile {
     public void setSecurityStatus(final SecureJar.Status status) {
         this.securityStatus = status;
     }
+
+    public ArtifactVersion getJarVersion()
+    {
+        return new DefaultArtifactVersion(this.jarVersion);
+    }
+
+    private static String parseType(final SecureJar jar) {
+        final Manifest m = jar.moduleDataProvider().getManifest();
+        final Optional<String> value = Optional.ofNullable(m.getMainAttributes().getValue(TYPE));
+        return value.orElse("MOD");
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModFileInfo.java

@@ -6,6 +6,7 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.google.common.base.Strings;
+import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
 import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.fml.loading.StringUtils;
@@ -13,8 +14,7 @@ import net.minecraftforge.forgespi.language.IConfigurable;
 import net.minecraftforge.forgespi.language.IModFileInfo;
 import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.forgespi.language.MavenVersionAdapter;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 import javax.security.auth.x500.X500Principal;
 import java.net.URL;
 import java.security.CodeSigner;
@@ -32,7 +32,7 @@ import java.util.stream.Stream;
 
 public class ModFileInfo implements IModFileInfo, IConfigurable
 {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
     private final IConfigurable config;
     private final ModFile modFile;
     private final URL issueURL;
@@ -43,6 +43,10 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
     private final String license;
     private final List<String> usesServices;
 
+    public static final String CLIENT_SIDE_ONLY_PROP = "__FORGE_clientSideOnly";
+
+    private static final Map<String, Object> CLIENT_SIDE_ONLY_MAP = Map.of(CLIENT_SIDE_ONLY_PROP, Boolean.TRUE);
+
     ModFileInfo(final ModFile modFile, final IConfigurable config)
     {
         this.modFile = modFile;
@@ -56,8 +60,21 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
         this.license = config.<String>getConfigElement("license")
             .orElse("");
         this.showAsResourcePack = config.<Boolean>getConfigElement("showAsResourcePack").orElse(false);
+        boolean clientSideOnly = config.<Boolean>getConfigElement("clientSideOnly").orElse(false);
         this.usesServices = config.<List<String>>getConfigElement("services").orElse(List.of());
-        this.properties = config.<Map<String, Object>>getConfigElement("properties").orElse(Collections.emptyMap());
+
+        var maybeProps = config.<Map<String, Object>>getConfigElement("properties");
+        if (clientSideOnly) {
+            if (maybeProps.isPresent()) {
+                this.properties = new HashMap<>(maybeProps.get());
+                this.properties.put(CLIENT_SIDE_ONLY_PROP, Boolean.TRUE);
+            } else {
+                this.properties = CLIENT_SIDE_ONLY_MAP;
+            }
+        } else {
+            this.properties = maybeProps.orElse(Collections.emptyMap());
+        }
+
         this.modFile.setFileProperties(this.properties);
         this.issueURL = config.<String>getConfigElement("issueTrackerURL").map(StringUtils::toURL).orElse(null);
         final List<? extends IConfigurable> modConfigs = config.getConfigList("mods");
@@ -68,10 +85,13 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
         this.mods = modConfigs.stream()
                 .map(mi-> new ModInfo(this, mi))
                 .collect(Collectors.toList());
-        LOGGER.debug(LogMarkers.LOADING, "Found valid mod file {} with {} mods - versions {}",
-                this.modFile::getFileName,
-                () -> this.mods.stream().map(IModInfo::getModId).collect(Collectors.joining(",", "{", "}")),
-                () -> this.mods.stream().map(IModInfo::getVersion).map(Objects::toString).collect(Collectors.joining(",", "{", "}")));
+        if (LOGGER.isDebugEnabled(LogMarkers.LOADING))
+        {
+            LOGGER.debug(LogMarkers.LOADING, "Found valid mod file {} with {} mods - versions {}",
+                    this.modFile.getFileName(),
+                    this.mods.stream().map(IModInfo::getModId).collect(Collectors.joining(",", "{", "}")),
+                    this.mods.stream().map(IModInfo::getVersion).map(Objects::toString).collect(Collectors.joining(",", "{", "}")));
+        }
     }
 
     public ModFileInfo(final ModFile file, final IConfigurable config, final List<LanguageSpec> languageSpecs) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModFileParser.java

@@ -8,12 +8,12 @@ package net.minecraftforge.fml.loading.moddiscovery;
 import com.electronwill.nightconfig.core.file.FileConfig;
 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.forgespi.language.IModFileInfo;
 import net.minecraftforge.forgespi.locating.IModFile;
 import net.minecraftforge.forgespi.locating.ModFileFactory;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.lang.reflect.Type;
@@ -25,7 +25,7 @@ import java.util.Map;
 import java.util.stream.Collectors;
 
 public class ModFileParser {
-    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogUtils.getLogger();
 
     public static IModFileInfo readModList(final ModFile modFile, final ModFileFactory.ModFileInfoParser parser) {
         return parser.build(modFile);