+ * Registers a listener to be notified about notification subscriptions. This
+ * enables a component to know when there is a notification listener subscribed
+ * for a particular notification type.
+ * <p>
+ * On registration of this listener, the
+ * {@link NotificationInterestListener#onNotificationSubscribtion(Class)} method
+ * will be invoked for every notification type that currently has a notification listener
+ * subscribed.
+ *
+ * @param interestListener the listener that will be notified when subscriptions
+ * for new notification types occur.
+ * @return a {@link ListenerRegistration} instance that should be used to unregister the listener
+ * by invoking the {@link ListenerRegistration#close()} method when no longer needed.