// null versus non-null.
    a = Arrays.<@Nullable Integer>asList(4, 8, 15, null, 23, 42);
    b = asList(4, 8, 15, 16, 23, 42);
    assertFalse(elementsEqual(a.iterator(), b.iterator()));
    assertFalse(elementsEqual(b.iterator(), a.iterator()));

    // Different lengths.
    a = asList(4, 8, 15, 16, 23);
    b = asList(4, 8, 15, 16, 23, 42);

    // null versus non-null.
    a = Arrays.<@Nullable Integer>asList(4, 8, 15, null, 23, 42);
    b = asList(4, 8, 15, 16, 23, 42);
    assertFalse(elementsEqual(a.iterator(), b.iterator()));
    assertFalse(elementsEqual(b.iterator(), a.iterator()));

    // Different lengths.
    a = asList(4, 8, 15, 16, 23);
    b = asList(4, 8, 15, 16, 23, 42);

   * of {@code iterator2}.
   *
   * <p>Note that this will modify the supplied iterators, since they will have been advanced some
   * number of elements forward.
   */
  public static boolean elementsEqual(Iterator<?> iterator1, Iterator<?> iterator2) {
    while (iterator1.hasNext()) {
      if (!iterator2.hasNext()) {
        return false;
      }
      Object o1 = iterator1.next();