Enhance documentation in mainline stubs am: ee390f26eb am: e8e98efe4b am: 111412e5c8

Original change: https://android-review.googlesource.com/c/platform/packages/modules/common/+/1827251

Change-Id: I220e59d7e03db5a434073b22f820bd613ca6cfc4

sdk/ModuleDefaults.bp

@@ -30,7 +30,8 @@ mainline_stubs_args =
     "--hide SdkConstant " +
     "--hide Todo " +
     "--hide Typo " +
-    "--hide UnavailableSymbol "
+    "--hide UnavailableSymbol " +
+    "--enhance-documentation "
 
 // TODO: modularize this so not every module has the same list
 framework_packages_to_document = [
@@ -76,8 +77,14 @@ mainline_service_stubs_args =
 java_defaults {
     name: "framework-module-common-defaults",
 
-    // Additional annotations used for compiling both the implementation and the
-    // stubs libraries.
+    // Use the source of annotations that affect metalava doc generation, since
+    // the relevant generation instructions are themselves in javadoc, which is
+    // not present in class files.
+    api_srcs: [":framework-metalava-annotations"],
+
+    // Make the source retention annotations available on the classpath when compiling
+    // the implementation library. (This should be in impl_only_libs but some modules
+    // use these defaults for java_library, sigh.)
     libs: ["framework-annotations-lib"],
 
     // Framework modules are not generally shared libraries, i.e. they are not