+ * Registers a {@link AsyncDataChangeListener} to receive
+ * notifications when data changes under a given path in the conceptual data
+ * tree.
+ * <p>
+ * You are able to register for notifications for any node or subtree
+ * which can be reached via the supplied path.
+ * <p>
+ * If path type <code>P</code> allows it, you may specify paths up to the leaf nodes
+ * then it is possible to listen on leaf nodes.
+ * <p>
+ * You are able to register for data change notifications for a subtree even
+ * if it does not exist. You will receive notification once that node is
+ * created.
+ * <p>
+ * If there is any preexisting data in data tree on path for which you are
+ * registering, you will receive initial data change event, which will
+ * contain all preexisting data, marked as created.
+ *
+ * <p>
+ * You are also able to specify the scope of the changes you want to be
+ * notified.
+ * <p>
+ * Supported scopes are:
+ * <ul>
+ * <li>{@link DataChangeScope#BASE} - notification events will only be
+ * triggered when a node referenced by path is created, removed or replaced.
+ * <li>{@link DataChangeScope#ONE} - notifications events will only be
+ * triggered when a node referenced by path is created, removed or replaced,
+ * or any or any of its immediate children are created, updated or removed.
+ * <li>{@link DataChangeScope#SUBTREE} - notification events will be
+ * triggered when a node referenced by the path is created, removed
+ * or replaced or any of the children in its subtree are created, removed
+ * or replaced.
+ * </ul>
+ * See {@link DataChangeScope} for examples.
+ * <p>
+ * This method returns a {@link ListenerRegistration} object. To
+ * "unregister" your listener for changes call the "close" method on this
+ * returned object.
+ * <p>
+ * You MUST call close when you no longer need to receive notifications
+ * (such as during shutdown or for example if your bundle is shutting down).