@NotNull
  @Override
  public NodeDescriptor createDescriptor(@NotNull Object element, NodeDescriptor parentDescriptor) {
    if (element == myTreeRoot || element instanceof RadComponent) {
      TreeNodeDescriptor descriptor = new TreeNodeDescriptor(parentDescriptor, element);
      descriptor.setWasDeclaredAlwaysLeaf(isAlwaysLeaf(element));
      return descriptor;
    }
    throw new IllegalArgumentException("Unknown element: " + element);
  }
@NotNull
  @Override
  public NodeDescriptor createDescriptor(@NotNull Object element, NodeDescriptor parentDescriptor)