docs: protected void sendMergeResponse(Address sender, View view, Digest digest, MergeId merge_id) {
          Message msg=new Message(sender).setBuffer(GMS.marshal(view, digest)).setFlag(Message.Flag.OOB,Message.Flag.INTERNAL)
            .putHeader(gms.getId(), new GMS.GmsHeader(GMS.GmsHeader.MERGE_RSP).mergeId(merge_id));
          gms.getDownProtocol().down(msg);
      }