Fix maven-plugin dependencies.

plugin-maven/CHANGES.md

@@ -6,6 +6,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ### Changed
 * Added support and bump Eclipse formatter default versions to `4.21` for `eclipse-groovy`. Change is only applied for JVM 11+.
 ### Fixed
+ * Fix plugin dependencies. Transitive Plexus Classworlds include can lead to  exceptions when resolving dependencies of Spotless plugins ([#397] https://github.com/diffplug/spotless/issues/397).
  * Revert change from 2.17.2 regarding [skip bug](https://github.com/diffplug/spotless/pull/969) because fixing the skip bug caused inconsistent behavior between `check.skip` and `apply.skip`.
  * [skip bug](https://github.com/diffplug/spotless/issues/968) if ratchetFrom is specified, the build will still fail in if no Git repository is found, even if `skip` is true (new fix).
 

plugin-maven/build.gradle

@@ -69,7 +69,9 @@ dependencies {
 		implementation "com.diffplug.spotless:spotless-lib-extra:${libVersion}"
 	}
 
-	implementation "org.codehaus.plexus:plexus-resources:${VER_PLEXUS_RESOURCES}"
+	implementation("org.codehaus.plexus:plexus-resources:${VER_PLEXUS_RESOURCES}") {
+		exclude group: 'classworld', module: 'classworld'
+	}
 	constraints {
 		implementation("org.codehaus.plexus:plexus-utils:3.4.1") {
 			because("version pulled by plexus-resources has a functional-bug affecting " +
@@ -80,7 +82,6 @@ dependencies {
 	compileOnly "org.apache.maven:maven-plugin-api:${VER_MAVEN_API}"
 	compileOnly "org.apache.maven.plugin-tools:maven-plugin-annotations:${VER_MAVEN_API}"
 	compileOnly "org.eclipse.aether:aether-api:${VER_ECLIPSE_AETHER}"
-	compileOnly "org.eclipse.aether:aether-util:${VER_ECLIPSE_AETHER}"
 
 	implementation "com.diffplug.durian:durian-core:${VER_DURIAN}"
 	implementation "com.diffplug.durian:durian-collect:${VER_DURIAN}"