@Nullable
  private static PackagingElementNode<?> findEqual(List<? extends PackagingElementNode<?>> children, PackagingElement<?> element) {
    for (PackagingElementNode<?> node : children) {
      if (node.getFirstElement().isEqualTo(element)) {
        return node;
      }
    }
    return null;
  }
@Nullable
  private static PackagingElementNode<?> findEqual(List<? extends PackagingElementNode<?>> children, PackagingElement<?> element)