code: public static List<Object> getLeafNodes(TreeModel treeModel, Object node)
      {
          List<Object> leafNodes = new ArrayList<Object>();
          getLeafNodes(treeModel, node, leafNodes);
          return leafNodes;
      }
docs: Returns a list containing all leaf nodes from the given tree model
  that are descendants of the given node. These are the nodes that
  have 0 children.
  
  @param treeModel The tree model
  @param node The node to start the search from
  @return The leaf nodes