Bug 156883 [Viewers] enhancements to ILazyTreeContentProvider
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
if (tree != null) {
					tree.setItemCount(count);
					return;
				}
				Widget[] items = findItems(element);
				for (int i = 0; i < items.length; i++) {
					TreeItem treeItem = (TreeItem) items[i];
					treeItem.setItemCount(count);
				}
			}
		});
	}
	/**
	 * For a TreeViewer with a tree with the VIRTUAL style bit set, replace the
	 * given parent's child at index with the given element. If the given parent
	 * is this viewer's input, this will replace the root element at the given
	 * index.
	 * <p>
	 * This method should be called by implementers of ILazyTreeContentProvider
	 * to populate this viewer.
	 * </p>
	 * 
	 * @param parent
	 *            the parent of the element that should be updated
	 * @param index
	 *            the index in the parent's children
	 * @param element
	 *            the new element
	 * 
	 * @see #setChildCount(Object, int)