Bug 156883 [Viewers] enhancements to ILazyTreeContentProvider
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
Assert.isTrue(tis[i].getData() == null,
									"Second or later child is non -null");
						}
						tis[i].dispose();
					}
				}
				Object d = widget.getData();
				if (d != null) {
					Object parentElement = d;
					Object[] children;
					if (isTreePathContentProvider() && widget instanceof Item) {
						TreePath path = getTreePathFromItem((Item) widget);
						children = getSortedChildren(path);
					} else {
						children = getSortedChildren(parentElement);
					}
					for (int i = 0; i < children.length; i++) {
						createTreeItem(widget, children[i], -1);
					}
				}
			}
		});
	}
	/**
	 * Creates a single item for the given parent and synchronizes it with the
	 * given element.
	 * 
	 * @param parent
	 *            the parent widget
	 * @param element