@ Override public void registerAttributeListener ( String attributeName , AttributeListener attributeListener ) { attributeListeners . putIfAbsent ( attributeName , new ArrayList < AttributeListener > ( ) ) ; List < AttributeListener > listeners = attributeListeners . get ( attributeName ) ; synchronized ( listeners ) { listeners . add ( attributeListener ) ; } }
Registers an attribute listener that gets notified in case the attribute changes . This is used for on change subscriptions .