build.gradle: don't use withSourcesJar()---it adds resources to the JAR

build.gradle

@@ -18,7 +18,6 @@ java {
     sourceCompatibility = JavaVersion.VERSION_1_7
     targetCompatibility = JavaVersion.VERSION_1_8
     withJavadocJar()
-    withSourcesJar()
 }
 
 dependencies {
@@ -71,6 +70,13 @@ jar {
     }
 }
 
+tasks.register('sourcesJar', Jar) {
+    archiveBaseName = project.ext.baseName
+    archiveClassifier = 'sources'
+    description 'Creates a JAR of Java sourcecode.'
+    from sourceSets.main.allJava // default is ".allSource", which include resources
+}
+
 assemble.dependsOn('module', 'moduleAsc', 'pom', 'pomAsc')
 tasks.register('module', Copy) {
     dependsOn 'generateMetadataFileForMavenPublication'
@@ -104,6 +110,7 @@ tasks.register('pomAsc', Copy) {
 publishing {
     publications {
         maven(MavenPublication) {
+            artifact sourcesJar
             artifactId artifact
             from components.java
             groupId project.ext.group