@Override
    public Optional<URL> handleHttpResponseException(ResponseException responseException)
        throws ResponseException, RegistryErrorException {
      throw responseException;
    }
Returns a URL to continue pushing the BLOB to, or {@link Optional#empty()} if the BLOB
already exists on the registry.
jib-core/src/main/java/com/google/cloud/tools/jib/registry/BlobPusher.java