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
for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            Object data = item.getData();
            TreePath childPath = data==null ? null: currentPath.createChildPath(data);
            if (data != null && childPath!=null) {
                
                
                boolean expanded = expandedTreePaths.remove(childPath) != null;
                if (expanded != getExpanded(item)) {
                    if (expanded) {
                        createChildren(item);
                    }
                    setExpanded(item, expanded);
                }
            }
            internalSetExpandedTreePaths(expandedTreePaths, item, childPath);
        }
	}
    /**
     * Return whether the tree node representing the given element or path can be
     * expanded. Clients should query expandablity by path if the viewer's
     * content provider is an {@link ITreePathContentProvider}.
     * <p>
     * The default implementation of this framework method calls <code>hasChildren</code>
     * on this viewer's content provider. It may be overridden if necessary.
     * </p>
     * 
     * @param elementOrTreePath
     *           the element or path
     * @return <code>true</code> if the tree node representing the given