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

      HostRoleCommand that = (HostRoleCommand) o;

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