@Nullable Enumeration<TreePath> getDescendantToggledPaths(@Nullable TreePath parent) {
      if (parent == null) {
        return null;
      }
      List<TreePath> descendants = new ArrayList<>();
      Set<TreePath> nodes = expandedState.keySet();
      for (var path : nodes) {
        if (parent.isDescendant(path)) {
          descendants.add(path);
        }
      }
      return Collections.enumeration(descendants);
    }
@Nullable Enumeration<TreePath> getDescendantToggledPaths(@Nullable TreePath parent)