Merge "Disallow missing api source files for java_api_library module" am: 0393174f

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2593068



Change-Id: Iabf6f35ecb320f1bcb78bf9118db40a23ceceeb2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>