private static boolean elementListsEqual(List<? extends Element> l1, List<? extends Element> l2) {
    if (l1 == null) return l2 == null;
    if (l2 == null) return false;

    if (l1.size() != l2.size()) return false;

    Iterator<? extends Element> i1 = l1.iterator();

    for (Element aL2 : l2) {
      Element elem1 = i1.next();

      if (!elementsEqual(elem1, aL2)) return false;
    }
    return true;
  }
private static boolean elementListsEqual(List<? extends Element> l1, List<? extends Element> l2)