docs: public void unpackMessage(Message.Builder builder) {
      int size = data.getInt();
      byte[] bytes = new byte[size];
      data.get(bytes);
      try {
        builder.mergeFrom(bytes);
      } catch (InvalidProtocolBufferException e) {
        LOG.log(Level.SEVERE, "InvalidProtocolBufferException: ", e);
      }
    }