Merge "Bp2build: handle the case where java_library has only proto srcs" into...

Merge "Bp2build: handle the case where java_library has only proto srcs" into main am: c90e1ec7 am: bc36c7e2

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2748099



Change-Id: I869460457bdfcbd5a70081cac7b67ad04aed3345
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>