question: void addPolicyListener ( PolicyListener policyListener ) { String listenerServiceName = policyListener . getServiceTypeName ( ) ; Set newListeners = new HashSet ( ) ; newListeners . add ( policyListener ) ; Set oldListeners = ( Set ) policyListenersMap . get ( listenerServiceName ) ; if ( oldListeners != null ) { newListeners . addAll ( oldListeners ) ; } policyListenersMap . put ( listenerServiceName , newListeners ) ; }
target:  Adds a policy listener. The policy listener would be notified whenever a policy is added/removed/changed.