@Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    super.toData(out, context);
    out.writeInt(listenerId);
    DataSerializer.writeObject(status, out);
  }
A message that is sent to a particular agent who was registered a health listener on a GemFireVM.
This message is only sent when the health status changes.

@since GemFire 3.5
geode-core/src/main/java/org/apache/geode/internal/admin/remote/HealthListenerMessage.java