final BackgroundObserver observer = createObserver(executor);
registration = new CompositeRegistration(
registerObserver(whiteboard, observer),
registerMBean(whiteboard, EventListenerMBean.class,
tracker.getListenerMBean(), "EventListener", tracker.toString()),
new Registration() {
@Override
public void unregister() {
observer.close();
}
},
new Registration() {
@Override
public void unregister() {
executor.stop();
}
});