public List getRuleBaseUpdateListeners() {
if ( this.ruleBaseListeners == null || this.ruleBaseListeners == Collections.EMPTY_LIST ) {
String listenerName = this.ruleBase.getConfiguration().getRuleBaseUpdateHandler();
if ( listenerName != null && listenerName.length() > 0 ) {
RuleBaseUpdateListener listener = RuleBaseUpdateListenerFactory.createListener( listenerName,
this );
this.ruleBaseListeners = Collections.singletonList( listener );
} else {
this.ruleBaseListeners = Collections.EMPTY_LIST;
}