@Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    // System.out.println("BEGIN AdminResponse toData");
    super.toData(out, context);
    out.writeInt(msgId);
    // System.out.println("END AdminResponse toData");
  }
This method is invoked on the side that sent the original AdminRequest.
geode-core/src/main/java/org/apache/geode/internal/admin/remote/AdminResponse.java