@NotNull
  public Collection<ResourceBundleEditorViewElement> getSelectedElements() {
    return getSelectedNodes()
      .filter(AbstractTreeNode.class)
      .filterMap(AbstractTreeNode::getValue)
      .filter(ResourceBundleEditorViewElement.class)
      .toList();
  }
@NotNull
  public Collection<ResourceBundleEditorViewElement> getSelectedElements()