Add more attributes to the classpath entries

Signed-off-by: sheche <[email protected]>

src/main/groovy/com/google/protobuf/gradle/Utils.groovy

@@ -156,6 +156,15 @@ class Utils {
         SourceFolder entry = new SourceFolder(relativePath, getOutputPath(cp, sourceSetName))
         entry.entryAttributes.put("optional", "true")
         entry.entryAttributes.put("ignore_optional_problems", "true")
+
+        entry.entryAttributes.put("gradle_scope", isTest ? "test" : "main")
+        entry.entryAttributes.put("gradle_used_by_scope", isTest ? "test" : "main,test")
+
+        // this attribute is optional, but it could be useful for IDEs to recognize that it is
+        // generated source folder from protobuf, thus providing some support for that.
+        // e.g. Hint user to run generate tasks if the folder is empty or does not exist.
+        entry.entryAttributes.put("protobuf_generated_source", "true")
+
         // check if output is not null here because test source folder
         // must have a separate output folder in Eclipse
         if (entry.output != null && isTest) {

src/test/groovy/com/google/protobuf/gradle/ProtobufJavaPluginTest.groovy

@@ -437,7 +437,16 @@ class ProtobufJavaPluginTest extends Specification {
 
     Set<String> sourceDir = [] as Set
     srcEntries.each {
-        sourceDir.add(it.@path)
+      String path = it.@path
+      sourceDir.add(path)
+      if (path.startsWith("build/generated/source/proto")) {
+        if (path.contains("test")) {
+          // test source path has one more attribute: ["test"="true"]
+          assert it.attributes.attribute.size() == 6
+        } else {
+          assert it.attributes.attribute.size() == 5
+        }
+      }
     }
 
     Set<String> expectedSourceDir = ImmutableSet.builder()