Bug 153993 [Viewers] Common Baseclass for Tree/TableEditorImpl
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
|| (provider instanceof ILazyTreePathContentProvider);
		contentProviderIsTreeBased = provider instanceof ILazyTreePathContentProvider;
		super.setContentProvider(provider);
	}
	
	/**
	 * For a TreeViewer with a tree with the VIRTUAL style bit set, inform the
	 * viewer about whether the given element or tree path has children. Avoid
	 * calling this method if the number of children has already been set.
	 * 
	 * @param elementOrTreePath
	 *            the element, or tree path
	 * @param hasChildren
	 * 
	 * @since 3.3
	 */
	public void setHasChildren(Object elementOrTreePath, boolean hasChildren) {
		if (internalIsInputOrEmptyPath(elementOrTreePath)) {
			if (hasChildren) {
				virtualLazyUpdateChildCount(getTree(), getChildren(getTree()).length);
			} else {
				setChildCount(elementOrTreePath, 0);
			}
			return;
		}
		Widget[] items = internalFindItems(elementOrTreePath);
		for (int i = 0; i < items.length; i++) {
				TreeItem item = (TreeItem) items[i];
				if (!hasChildren) {
					item.setItemCount(0);