Downgrade shadowJar instead of libraries

build.gradle

@@ -16,32 +16,25 @@ buildscript {
     }
 }
 
-apply plugin: "java-library"
-apply plugin: "xyz.wagyourtail.jvmdowngrader"
-
-System.setProperty("jvmdg.quiet", "true")
-
-java {
-    toolchain.languageVersion = JavaLanguageVersion.of(17)
-}
-
 allprojects {
     apply plugin: "java-library"
     apply plugin: "com.github.johnrengelman.shadow"
     apply plugin: "me.modmuss50.mod-publish-plugin"
+    apply plugin: "xyz.wagyourtail.jvmdowngrader"
+
+    java {
+        // Minecraft 1.17+ required Java 16/17 to compile
+        toolchain.languageVersion = JavaLanguageVersion.of(17)
+    }
+
 
     // We define the configuration here so we can use it across all conventions and platforms
     // To define which projects/source files should be included in the jar
     configurations {
         library
         implementation.extendsFrom(library)
-
-        libraryJ8
-        library.extendsFrom(libraryJ8)
     }
 
-    jvmdg.dg(configurations.libraryJ8)
-
     // Repositories for the ViaVersion dependencies defined below
     repositories {
         maven {
@@ -50,7 +43,7 @@ allprojects {
         maven {
             url = "https://repo.viaversion.com"
             metadataSources {
-                // Cursed hack to prevent Gradle checking for Java versions
+                mavenPom()
                 artifact()
             }
         }
@@ -72,14 +65,14 @@ allprojects {
     dependencies {
         compileOnly "io.netty:netty-all:4.0.20.Final"
 
-        libraryJ8 "com.viaversion:viaversion-common:${project.viaversion_version}"
-        libraryJ8 "com.viaversion:viabackwards-common:${project.viabackwards_version}"
-        libraryJ8 "com.viaversion:viarewind-common:${project.viarewind_version}"
-        libraryJ8 ("net.raphimc:ViaLegacy:${project.vialegacy_version}") {
+        library "com.viaversion:viaversion-common:${project.viaversion_version}"
+        library "com.viaversion:viabackwards-common:${project.viabackwards_version}"
+        library "com.viaversion:viarewind-common:${project.viarewind_version}"
+        library ("net.raphimc:ViaLegacy:${project.vialegacy_version}") {
             exclude group: "com.google.code.gson", module: "gson"
         }
-        libraryJ8 "net.raphimc:ViaAprilFools:${project.viaaprilfools_version}"
-        libraryJ8 ("net.raphimc:ViaLoader:${project.vialoader_version}") {
+        library "net.raphimc:ViaAprilFools:${project.viaaprilfools_version}"
+        library ("net.raphimc:ViaLoader:${project.vialoader_version}") {
             exclude group: "com.google.guava"
             exclude group: "org.slf4j"
         }
@@ -167,18 +160,12 @@ subprojects {
         enabled = false
     }
 
-    tasks.withType(JavaCompile).configureEach {
-        if (versionId >= 1_17_1) {
-            sourceCompatibility = JavaVersion.VERSION_17
-            targetCompatibility = JavaVersion.VERSION_17
-        } else {
-            sourceCompatibility = JavaVersion.VERSION_1_8
-            targetCompatibility = JavaVersion.VERSION_1_8
-        }
-    }
-
     shadowJar {
+        if (versionId >= 1_17_1) {
             archiveFileName = jar.archiveFileName
+        } else {
+            destinationDirectory = temporaryDir
+        }
         configurations = [project.configurations.library] // Include the dependencies from the include configuration
         duplicatesStrategy DuplicatesStrategy.EXCLUDE
 
@@ -197,6 +184,15 @@ subprojects {
         }
     }
 
+    downgradeJar {
+        inputFile = shadowJar.archiveFile
+        destinationDirectory = temporaryDir
+    }
+
+    shadeDowngradedApi {
+        archiveFileName = jar.archiveFileName
+    }
+
     publishMods {
         file = shadowJar.archiveFile
         type = STABLE
@@ -223,4 +219,8 @@ subprojects {
     }
 
     jar.dependsOn("shadowJar")
+    if (versionId < 1_17_1) {
+        // Downgrade the jar to Java 8 for Minecraft 1.16.5 and below
+        jar.dependsOn("shadeDowngradedApi")
+    }
 }