@NotNull
  private CheckedTreeNode addGroupNode(@NotNull ToolsGroup<T> group) {
    CheckedTreeNode groupNode = new CheckedTreeNode(group);
    getTreeRoot().add(groupNode);
    for (T tool : group.getElements()) {
      addToolNode(groupNode, tool);
    }
    return groupNode;
  }
@NotNull
  private CheckedTreeNode addGroupNode(@NotNull ToolsGroup<T> group)