static @Nullable String getActionId(DefaultMutableTreeNode node) {
    Object obj = node.getUserObject();
    if (obj instanceof String actionId) return actionId;
    if (obj instanceof Group group) return group.getId();
    if (obj instanceof Pair<?, ?> pair) {
      Object first = pair.first;
      return first instanceof Group group ? group.getId() : (String)first;
    }
    return null;
  }
static @Nullable String getActionId(DefaultMutableTreeNode node)