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 tcp.hasChildren(element);	
		}
		return false;
    }
    
    /**
     * Return whether the given element is expandable.
     * @param item the tree item for the element
     * @param parentPath the parent path if it is knwon or <code>null</code> if it needs to be determines
     * @param element the element
     * @return whether the given element is expandable
     */
    private boolean isExpandable(Item item, TreePath parentPath, Object element) {
    	if (isTreePathContentProvider()) {
    		TreePath path;
    		if (parentPath != null) {
    			path = parentPath.createChildPath(element);
    		} else {
    			path = getTreePathFromItem(item);
    		}
    		ITreePathContentProvider cp = (ITreePathContentProvider) getContentProvider();
    		return cp != null && cp.hasChildren(path);
    	}
    	return isExpandable(element);
    }
    
    
    protected void labelProviderChanged() {
        
        Control tree = getControl();