Remove java < 11 support for yarns buildscript. (#2296)

.github/workflows/build.yml

@@ -4,7 +4,7 @@ jobs:
   build:
     strategy:
       matrix:
-        java: [8-jdk, 11-jdk, 15-jdk]
+        java: [11-jdk, 15-jdk]
     runs-on: ubuntu-20.04
     container:
       image: openjdk:${{ matrix.java }}

build.gradle

@@ -777,12 +777,6 @@ task sourcesJar(type: Jar, dependsOn: classes) {
 
 compilePackageDocsJava {
 	it.options.encoding = "UTF-8"
-	// use java 11 as the package info files aren't consumed by downstream java 8 mods etc.
-	if (!JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_11)) {
-		javaCompiler = javaToolchains.compilerFor {
-			languageVersion = JavaLanguageVersion.of(11)
-		}
-	}
 	it.options.release = 11
 }
 
@@ -885,12 +879,6 @@ task genFakeSource(type: JavaExec, dependsOn: ["mergeV2", "mapNamedJar"]) {
 	group = "javadoc generation"
 	outputs.upToDateWhen { false }
 
-	if (!JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_11)) {
-		javaLauncher = javaToolchains.launcherFor {
-			languageVersion = JavaLanguageVersion.of(11)
-		}
-	}
-
 	main "net.fabricmc.mappingpoet.Main"
 	classpath configurations.mappingPoet
 	// use merged v2 so we have all namespaces in jd
@@ -924,11 +912,6 @@ javadoc {
 
 	failOnError = false
 
-	if (!JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_11)) {
-		javadocTool = javaToolchains.javadocToolFor {
-			languageVersion = JavaLanguageVersion.of(11)
-		}
-	}
 	// verbose = true // enable to debug
 	options {
 		// verbose() // enable to debug

settings.gradle

@@ -1,3 +1,8 @@
+// This check is done here before any plugins that may require java 11 are able to load.
+if (!JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_11)) {
+    throw new UnsupportedOperationException("Yarn's buildscript requires Java 11 or higher.")
+}
+
 rootProject.name = "yarn"
 
 includeBuild 'build-logic'