*     a provided list is null
   * @since 19.0
   */
  public static <B> List<List<B>> cartesianProduct(List<? extends List<? extends B>> lists) {
    return CartesianList.create(lists);
  }

  /**
   * Returns every possible list that can be formed by choosing one element from each of the given

    assertEquals(asList(1, 4, 7, 8, 9, 10), newArrayList(result));
    assertEquals("[1, 4, 7, 8, 9, 10]", result.toString());
  }

  public void testConcatNullPointerException() {
    List<Integer> list1 = newArrayList(1);
    List<Integer> list2 = newArrayList(4);

    try {
      FluentIterable.concat(list1, null, list2);
      fail();

    List<@Nullable Integer> list1 = Lists.newArrayList();
    List<@Nullable Integer> list2 = Lists.newArrayList(1);
    List<@Nullable Integer> list3 = Lists.newArrayList(1, 1);
    List<@Nullable Integer> list4 = Lists.newArrayList(1, 2);
    List<@Nullable Integer> list5 = Lists.newArrayList(1, null, 2);
    List<@Nullable Integer> list6 = Lists.newArrayList(2);

    List<@Nullable Integer> list1 = Lists.newArrayList();
    List<@Nullable Integer> list2 = Lists.newArrayList(1);
    List<@Nullable Integer> list3 = Lists.newArrayList(1, 1);
    List<@Nullable Integer> list4 = Lists.newArrayList(1, 2);
    List<@Nullable Integer> list5 = Lists.newArrayList(1, null, 2);
    List<@Nullable Integer> list6 = Lists.newArrayList(2);

    assertThat(Lists.hashCodeImpl(base)).isNotEqualTo(Lists.hashCodeImpl(outOfOrder));
    assertThat(Lists.hashCodeImpl(base)).isNotEqualTo(Lists.hashCodeImpl(diffValue));
    assertThat(Lists.hashCodeImpl(base)).isNotEqualTo(Lists.hashCodeImpl(diffLength));
    assertThat(Lists.hashCodeImpl(base)).isNotEqualTo(Lists.hashCodeImpl(empty));
  }

  public void testEqualsImpl() {

    final List<Object> annotatedIn1Events = Lists.newArrayList();
    final List<Object> annotatedIn1And2Events = Lists.newArrayList();
    final List<Object> annotatedIn1And2AndClassEvents = Lists.newArrayList();
    final List<Object> declaredIn1AnnotatedIn2Events = Lists.newArrayList();
    final List<Object> declaredIn1AnnotatedInClassEvents = Lists.newArrayList();

    try {
      multimap().putAll(k3(), Lists.newArrayList(v3(), null));
      fail();
    } catch (NullPointerException expected) {
    }

    Collection<V> values = multimap().get(k3());
    if (values.size() == 0) {
      expectUnchanged();
      // Be extra thorough in case internal state was corrupted by the expected null.
      assertEquals(Lists.newArrayList(), Lists.newArrayList(values));

    assertEquals(list, newArrayList(Iterators.limit(list.iterator(), 1)));
    assertEquals(list, newArrayList(Iterators.limit(list.iterator(), 2)));

    list.add("pants");
    assertFalse(Iterators.limit(list.iterator(), 0).hasNext());
    assertEquals(ImmutableList.of("cool"), newArrayList(Iterators.limit(list.iterator(), 1)));
    assertEquals(list, newArrayList(Iterators.limit(list.iterator(), 2)));

    bus.register(hater);

    bus.post(FIRST);

    assertEquals(
        "ReentrantEventHater expected 2 events",
        Lists.<Object>newArrayList(FIRST, SECOND),
        hater.eventsReceived);
  }

  public class ReentrantEventsHater {
    boolean ready = true;
    List<Object> eventsReceived = Lists.newArrayList();

    @Subscribe
    public void listenForStrings(String event) {
      eventsReceived.add(event);

    assertEquals(asList(1, 4, 7, 8, 9, 10), newArrayList(result));
    assertEquals("[1, 4, 7, 8, 9, 10]", result.toString());
  }

  public void testConcatNullPointerException() {
    List<Integer> list1 = newArrayList(1);
    List<Integer> list2 = newArrayList(4);

    try {
      Iterables.concat(list1, null, list2);
      fail();
    } catch (NullPointerException expected) {