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
}
    }
    /**
     * Returns the auto-expand level.
     * 
     * @return non-negative level, or <code>ALL_LEVELS</code> if all levels
     *         of the tree are expanded automatically
     * @see #setAutoExpandLevel
     */
    public int getAutoExpandLevel() {
        return expandToLevel;
    }
    /**
     * Returns the SWT child items for the given SWT widget.
     * 
     * @param widget
     *           the widget
     * @return the child items
     */
    protected abstract Item[] getChildren(Widget widget);
	
	/**
	 * Get the child for the widget at index. Note that the default
	 * implementation is not very effecient and should be overridden
	 * if this class is implemented.
	 * @param widget the widget to check
	 * @param index the index of the widget
	 * @return Item or <code>null</code> if widget is not a type
	 * that can contain items.
     *