@Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;

    ServiceUpdateEvent that = (ServiceUpdateEvent) o;

    if (clusterName != null ? !clusterName.equals(that.clusterName) : that.clusterName != null) return false;
    return serviceName != null ? serviceName.equals(that.serviceName) : that.serviceName == null;
  }
Contains info about service update. This update will be sent to all subscribed recipients.
ambari-server/src/main/java/org/apache/ambari/server/events/ServiceUpdateEvent.java