@Override
    public void toData(DataOutput out, SerializationContext context) throws IOException {
      super.toData(out, context);
      out.writeInt(processorId);
    }
SerialAckedMessageWithBigReply requires conserve-sockets=false and acts to send
a large reply message to the sender. You must have already created a cache in the
sender and receiver VMs and registered this class with the DataSerializableFixedID
of SERIAL_ACKED_MESSAGE. Don't forget to reset the registration to
SerialAckedMessage at the end of the test.
geode-core/src/upgradeTest/java/org/apache/geode/ClusterCommunicationsDUnitTest.java