Bug 122756 [Viewers] Support for TreePath based content providers
Now that the JFace tree viewer supports the notion of a tree path, it would be benefitial if this information was made available to content providers and label providers. The particular scenario that requires this is team views that include change sets. A view can display multiple change sets and a single model element may be included in multiple change sets. In 3.2, we are using the common navigator framework to allow model providers to display their models in a team operation. Having a tree path based content provider would allow the logical model display to be intermixed with change sets. Without this support, team providers would most likely need to support two views, one which shows resources and change sets and another that shows the effects of the operation on the logical model.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*           the element or tree path
     * @param level
     *           non-negative level, or <code>ALL_LEVELS</code> to collapse
     *           all levels of the tree
     */
    public void collapseToLevel(Object elementOrTreePath, int level) {
        Assert.isNotNull(elementOrTreePath);
        Widget w = internalGetWidgetToSelect(elementOrTreePath);
        if (w != null)
            internalCollapseToLevel(w, level);
    }
    /**
     * Creates all children for the given widget.
     * <p>
     * The default implementation of this framework method assumes that <code>widget.getData()</code>
     * returns the element corresponding to the node. Note: the node is not
     * visually expanded! You may have to call <code>parent.setExpanded(true)</code>.
     * </p>
     * 
     * @param widget
     *           the widget
     */
    protected void createChildren(final Widget widget) {
        final Item[] tis = getChildren(widget);
        if (tis != null && tis.length > 0) {
            Object data = tis[0].getData();
            if (data != null)
                return; 
        }
        BusyIndicator.showWhile(widget.getDisplay(), new Runnable() {