@Override
 public void writeTo(StreamOutput out) throws IOException {
   super.writeTo(out);
   out.writeByte(status.id());
   out.writeVLong(size);
 }
 @Override
 public void readFrom(StreamInput in) throws IOException {
   super.readFrom(in);
   status = RemoteDigestBlob.Status.fromId(in.readByte());
   size = in.readVLong();
 }