Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/TreeViewerUpdatableTree.java
Object parent;
		List   children;
		boolean requestedChildren=false;
		private TreeNode(Object parent, List children) {
			this.parent=parent;
			this.children=children;			
		}
		private TreeNode(Object parent) {
			this(parent, null);
		}
		/**
		 * @return a List, the children of this node
		 */
		public List getChildren() {
			return children;
		}
		/**