private void broadcastCollectionNodeEvent(Node child, Message notification) {
        // Get affected subscriptions (of this node and all parent nodes)
        Collection<NodeSubscription> subscriptions = new ArrayList<>();
        subscriptions.addAll(getSubscriptions(child));
        for (CollectionNode parentNode : getParents()) {
            subscriptions.addAll(parentNode.getSubscriptions(child));
        }
        // TODO Possibly use a thread pool for sending packets (based on the jids size)
        for (NodeSubscription subscription : subscriptions) {
            getService().sendNotification(subscription.getNode(), notification, subscription.getJID());
        }
        Log.trace("Broadcast event notification to {} subscriber(s) of node '{}'.", subscriptions.size(), child.getNodeID());

        // XEP-0136 specifies that all connected resources of the owner of the PEP service should also get a notification
        if (getService() instanceof PEPService) {
            final Collection<ClientSession> sessions = SessionManager.getInstance().getSessions(getService().getAddress().getNode());
            Log.trace("Send event notification to {} PEP owner session(s) of node '{}'.", sessions, child.getNodeID());
            for( final ClientSession session : sessions ) {
                getService().sendNotification(child, notification, session.getAddress());
                Log.trace("Send event notification to {} PEP owner session(s) of {} parent node(s) of '{}'.", sessions, getParents().size(), child.getNodeID());
                for (CollectionNode parentNode : getParents()) {
                    getService().sendNotification(parentNode, notification, session.getAddress());
                }
            }
        }
    }
Notification that a child node was deleted from this node. Trigger notifications
to node subscribers whose subscription type is {@link NodeSubscription.Type#nodes} and
have the proper depth.

@param child the deleted node that was removed from this node.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/CollectionNode.java