Bug 171649 [Viewers] AbstractTreeViewerisExpandable(elementOrTreePath) is not called when using a ITreePathContentProvider
Build ID: 3.3M3 More information: see AbstractTreeViewer.java, line 1974, the content provider hasChildren() should not be called directly
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
if (siblings[i] == item && i < (siblings.length - 1)) {
					return siblings[i + 1];
				}
			}
		}
		return getNextItem(parent, false);
	}
	/**
	 * Returns the parent item of the given item in the tree, or
	 * <code>null</code> if there is no parent item.
	 * 
	 * @param item
	 *            the item
	 * @return the parent item, or <code>null</code> if none
	 */
	protected abstract Item getParentItem(Item item);
	/**
	 * Returns the item before the given item in the tree, or <code>null</code>
	 * if there is no previous item.
	 * 
	 * @param item
	 *            the item
	 * @return the previous item, or <code>null</code> if none
	 */
	protected Item getPreviousItem(Item item) {
		
		
		Item parent = getParentItem(item);
		if (parent == null) {
			return null;