Always drop deps from android_library with no srcs

android_library does not accept deps when there are no srcs because
there is no compilation happening. The libs of android_library module
are unnecessary as deps on the android_library since they aren't
being propagated to any dependencies.
So we can drop deps here.

Test: the updated test case and CI

Bug: 302290600

Change-Id: Ib43a1c273a5f3b3e0aa6f29f4e8569ad3487e451
diff --git a/java/aar.go b/java/aar.go
index 6f3d915..cc51b8c 100644
--- a/java/aar.go
+++ b/java/aar.go
@@ -1344,10 +1344,12 @@
 	if !commonAttrs.Srcs.IsEmpty() {
 		deps.Append(depLabels.StaticDeps) // we should only append these if there are sources to use them
 	} else if !depLabels.Deps.IsEmpty() {
-		ctx.MarkBp2buildUnconvertible(
-			bp2build_metrics_proto.UnconvertedReasonType_UNSUPPORTED,
-			"Module has direct dependencies but no sources. Bazel will not allow this.")
-		return
+		// android_library does not accept deps when there are no srcs because
+		// there is no compilation happening, but it accepts exports.
+		// The non-empty deps here are unnecessary as deps on the android_library
+		// since they aren't being propagated to any dependencies.
+		// So we can drop deps here.
+		deps = bazel.LabelListAttribute{}
 	}
 	name := a.Name()
 	props := AndroidLibraryBazelTargetModuleProperties()