@Nullable Enumeration<TreePath> getExpandedDescendants(@Nullable TreePath parent) {
      if (parent == null || !isExpanded(parent)) {
        return null;
      }
      Set<TreePath> toggledPaths = expandedState.keySet();
      List<TreePath> elements = null;
      for (var path : toggledPaths) {
        var value = expandedState.get(path);
        if (!path.equals(parent) && value != null && value.booleanValue() && parent.isDescendant(path) && isVisible(path)) {
          if (elements == null) {
            elements = new ArrayList<>();
          }
          elements.add(path);
        }
      }
      return elements == null ? Collections.emptyEnumeration() : Collections.enumeration(elements);
    }
@Nullable Enumeration<TreePath> getExpandedDescendants(@Nullable TreePath parent)