code: static <E> boolean addAllImpl(List<E> list, int index, Iterable<? extends E> elements) {
      boolean changed = false;
      ListIterator<E> listIterator = list.listIterator(index);
      for (E e : elements) {
        listIterator.add(e);
        changed = true;
      }
      return changed;
    }
docs: An implementation of {@link List#addAll(int, Collection)}.