xds: add proto leakage check at gradle build (#7899)
xds: add proto leakage check at gradle build (#7899)


grpc/grpc-java,dapengzhang0/grpc-java,dapengzhang0/grpc-java,grpc/grpc-java,stanley-cheung/grpc-java,grpc/grpc-java,stanley-cheung/grpc-java,ejona86/grpc-java,dapengzhang0/grpc-java,ejona86/grpc-java,stanley-cheung/grpc-java,dapengzhang0/grpc-java,stanley-cheung/grpc-java,ejona86/grpc-java,ejona86/grpc-java,grpc/grpc-java