* undocumented and subject to change.
   *
   * <p>Note that if {@code list} is a {@code List<String>}, then {@code ImmutableList.copyOf(list)}
   * returns an {@code ImmutableList<String>} containing each of the strings in {@code list}, while
   * {@code ImmutableList.of(list)} returns an {@code ImmutableList<List<String>>} containing one
   * element (the given list itself).
   *

  @SuppressWarnings("unchecked")
  public static <E> ImmutableList<E> of() {
    return (ImmutableList<E>) RegularImmutableList.EMPTY;
  }

  public static <E> ImmutableList<E> of(E element) {
    return new SingletonImmutableList<E>(checkNotNull(element));
  }

  public static <E> ImmutableList<E> of(E e1, E e2) {
    return new RegularImmutableList<E>(ImmutableList.<E>nullCheckedList(e1, e2));
  }

   * undocumented and subject to change.
   *
   * <p>Note that if {@code list} is a {@code List<String>}, then {@code ImmutableList.copyOf(list)}
   * returns an {@code ImmutableList<String>} containing each of the strings in {@code list}, while
   * {@code ImmutableList.of(list)} returns an {@code ImmutableList<List<String>>} containing one
   * element (the given list itself).
   *

    ImmutableList<Integer>[] array =
        (ImmutableList<Integer>[]) new ImmutableList<?>[] {ImmutableList.of(1)};
    TypeToken<ImmutableList<Integer>[]> type = new TypeToken<ImmutableList<Integer>[]>() {};
    ImmutableTypeToInstanceMap<Iterable<?>[]> map =
        ImmutableTypeToInstanceMap.<Iterable<?>[]>builder().put(type, array).build();
    assertEquals(1, map.size());

      return (ImmutableRangeMap<K, V>) rangeMap;
    }
    Map<Range<K>, ? extends V> map = rangeMap.asMapOfRanges();
    ImmutableList.Builder<Range<K>> rangesBuilder = new ImmutableList.Builder<>(map.size());
    ImmutableList.Builder<V> valuesBuilder = new ImmutableList.Builder<>(map.size());
    for (Entry<Range<K>, ? extends V> entry : map.entrySet()) {
      rangesBuilder.add(entry.getKey());
      valuesBuilder.add(entry.getValue());
    }

    List<Iterable<String>> toAdd =
        ImmutableList.of(
            Collections.singleton("A"),
            Collections.emptyList(),
            ImmutableList.of("A", "B", "C"),
            ImmutableList.of("D", "E"));
    List<Integer> indexes = ImmutableList.of(0, 0, 1, 3);
    List<List<String>> expected =
        ImmutableList.of(
            ImmutableList.of("A"),
            ImmutableList.of("A"),

  }

  private transient @Nullable ImmutableList<E> asList;

  public ImmutableList<E> asList() {
    ImmutableList<E> list = asList;
    return (list == null) ? (asList = createAsList()) : list;
  }

  ImmutableList<E> createAsList() {
    switch (size()) {
      case 0:
        return ImmutableList.of();
      case 1:
        return ImmutableList.of(iterator().next());
      default:

    EquivalenceTester.of(Equivalence.equals().<String>pairwise())
        .addEquivalenceGroup(ImmutableList.<String>of())
        .addEquivalenceGroup(ImmutableList.of("a"))
        .addEquivalenceGroup(ImmutableList.of("b"))
        .addEquivalenceGroup(ImmutableList.of("a", "b"), ImmutableList.of("a", "b"))
        .test();
  }

  public void testPairwiseEquivalent_equals() {
    new EqualsTester()

    List<Optional<String>> optionals =
        ImmutableList.of(Optional.of("a"), Optional.of("b"), Optional.of("c"));
    assertThat(Optional.presentInstances(optionals)).containsExactly("a", "b", "c").inOrder();
  }

  public void testPresentInstances_allAbsent() {
    List<Optional<Object>> optionals = ImmutableList.of(Optional.absent(), Optional.absent());

    ImmutableList<Integer>[] array =
        (ImmutableList<Integer>[]) new ImmutableList<?>[] {ImmutableList.of(1)};
    TypeToken<ImmutableList<Integer>[]> type = new TypeToken<ImmutableList<Integer>[]>() {};
    ImmutableTypeToInstanceMap<Iterable<?>[]> map =
        ImmutableTypeToInstanceMap.<Iterable<?>[]>builder().put(type, array).build();
    assertEquals(1, map.size());