deps: update dependency com.google.protobuf:protobuf-java to v3.15.1 (#1270)
deps: update dependency com.google.protobuf:protobuf-java to v3.15.1 (#1270)


googleapis/google-http-java-client,googleapis/google-http-java-client,googleapis/google-http-java-client,googleapis/google-http-java-client