void removeChildNode(Node child) {
        Log.trace("Remove child node: {}", child.getNodeID());
        nodes.remove(child.getUniqueIdentifier());
    }
Removes a child node from the list of child nodes. This method will not trigger
notifications to node subscribers.

@param child the node to remove from the list of child nodes.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/CollectionNode.java