code: <T extends INode> T addNode(String path, T newNode, boolean inheritPermission
        ) throws FileNotFoundException {
      byte[][] pathComponents = getPathComponents(path);
      if(addToParent(pathComponents, newNode, inheritPermission, true) == null)
        return null;
      return newNode;
    }
docs: Add new INode to the file tree.
  Find the parent and insert
  
  @param path file path
  @param newNode INode to be added
  @param inheritPermission If true, copy the parent's permission to newNode.
  @return null if the node already exists; inserted INode, otherwise
  @throws FileNotFoundException if parent does not exist or
  is not a directory.