Fix not including non java code in sources jar (#25)

Co-authored-by: Martin Robertz <dream-master@gmx.net>

build.gradle

@@ -462,7 +462,7 @@ def getManifestAttributes() {
 }
 
 task sourcesJar(type: Jar) {
-    from (sourceSets.main.allJava)
+    from (sourceSets.main.allSource)
     from (file("$projectDir/LICENSE"))
     getArchiveClassifier().set('sources')
 }
@@ -517,7 +517,7 @@ task devJar(type: Jar) {
 }
 
 task apiJar(type: Jar) {
-    from (sourceSets.main.allJava) {
+    from (sourceSets.main.allSource) {
         include modGroup.toString().replaceAll("\\.", "/") + "/" + apiPackage.toString().replaceAll("\\.", "/") + '/**'
     }