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
return null;
    }
    /**
     * Recursively tries to find the given element.
     * 
     * @param parent
     *           the parent item
     * @param element
     *           the element
     * @return Widget
     */
    private Widget internalFindItem(Item parent, Object element) {
        
        Object data = parent.getData();
        if (data != null) {
            if (equals(data, element)) {
				return parent;
			}
        }
        
        Item[] items = getChildren(parent);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            Widget o = internalFindItem(item, element);
            if (o != null) {
				return o;
			}
        }
        return null;
    }