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

    HostComponentsUpdateEvent that = (HostComponentsUpdateEvent) o;

    return hostComponentUpdates != null ? hostComponentUpdates.equals(that.hostComponentUpdates) : that.hostComponentUpdates == null;
  }
Contains list of updated hostcomponents. This update will be sent to all subscribed recipients.
ambari-server/src/main/java/org/apache/ambari/server/events/HostComponentsUpdateEvent.java