@Override
  protected void prepareBuffer() {
    super.prepareBuffer();
    Utils.serializeString(bufferToSend, hostName, Charset.defaultCharset());
    bufferToSend.writeBytes(partitionId.getBytes());
  }
Prepare the buffer to be sent over the network.
ambry-protocol/src/main/java/com/github/ambry/protocol/FileCopyGetMetaDataRequest.java