code: public ChildData getCurrentData(String fullPath)
      {
          TreeNode node = find(fullPath);
          if ( node == null || node.nodeState != NodeState.LIVE )
          {
              return null;
          }
          ChildData result = node.childData;
          // Double-check liveness after retreiving data.
          return node.nodeState == NodeState.LIVE ? result : null;
      }
docs: Return the current data for the given path. There are no guarantees of accuracy. This is
  merely the most recent view of the data. If there is no node at the given path,
  {@code null} is returned.
  
  @param fullPath full path to the node to check
  @return data if the node is alive, or null