Include Groovy source code in published sources jars

In our Gradle build script, we are now assembling 'sources' jars from
'sourceSets.main.allSource' in order to include Java, Groovy, and
AspectJ source code as well all other appropriate classpath resources.

Issue: SPR-12086

build.gradle

@@ -229,8 +229,7 @@ configure(subprojects - project(":spring-build-src")) { subproject ->
 
 	task sourcesJar(type: Jar, dependsOn: classes) {
 		classifier = 'sources'
-		from sourceSets.main.allJava.srcDirs, sourceSets.main.resources.srcDirs
-		// sourceSets.main.allGroovy.srcDirs can only be applied to groovy projects
+		from sourceSets.main.allSource
 		include '**/*.java'
 		include '**/*.groovy'
 		include '**/*.aj'