Bug 130976 [Viewers] Error is calculation of parent path when calling TreePathViewerSorter
There is an error in the parent path calculation in AbstractTreeViewer#getSortedChildren. If the input of the viewer is passed, a tee path of length one is passed to the sorter but a null should be passed (as mentioned in the method spec). I will attach a patch.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
internalCollectVisibleExpanded(v, getControl());
        return v.toArray();
    }
    private void internalCollectVisibleExpanded(ArrayList result, Widget widget) {
        Item[] items = getChildren(widget);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            if (getExpanded(item)) {
                Object data = item.getData();
                if (data != null) {
					result.add(data);
				}
                
                
                internalCollectVisibleExpanded(result, item);
            }
        }
    }
    /**
     * Returns the tree path for the given item.
     *  
     * @since 3.2
     */
    protected TreePath getTreePathFromItem(Item item) {
		LinkedList segments = new LinkedList();
		while(item!=null) {
			Object segment = item.getData();
			Assert.isNotNull(segment);
			segments.addFirst(segment);
			item = getParentItem(item);