@Override
  public void fromData(DataInput in,
      DeserializationContext context) throws IOException, ClassNotFoundException {
    super.fromData(in, context);
    alertLevel = in.readInt();
  }
Sent by JMX manager to all other members to notify them that it has started.
geode-core/src/main/java/org/apache/geode/management/internal/ManagerStartupMessage.java