Bug 184755 [DataBinding] internal tree content provider does not work
I broke the tree content providers while trying to update them to use TreePaths. It would be good to have a working implementation again...
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/internal/viewers/UnorderedTreeNode.java
* Returns the set of children for this node. If new children are discovered later, they
     * will be added directly to the viewer.
     *  
     * @return the set of children
     */
    public Set getChildren() {
        if (!listeningToChildren) {
            listeningToChildren = true;
            children.addSetChangeListener(this);
            hasPendingNode = children.isEmpty() && children.isStale();
            children.addStaleListener(this);
            updateStale();
        }
        
        
        if (hasPendingNode) {
            Object pendingNode = contentProvider.getPendingNode();
            return Collections.singleton(pendingNode);
        }
        return children;
    }
    
    /**
     * @return the observable set of children
     */
    public IObservableSet getChildrenSet() {
        return children;
    }
    
    private void updateStale() {