* first specified. That is, if multiple elements are {@linkplain Object#equals equal}, all except
   * the first are ignored.
   */
  public static <E> ImmutableSet<E> of(E e1, E e2) {
    return new RegularSetBuilderImpl<E>(2).add(e1).add(e2).review().build();
  }

  /**
   * Returns an immutable set containing the given elements, minus duplicates, in the order each was

  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ZERO)
  public void putDistinctKeysDistinctValues() {
    getMap().put(k0(), v0());
    getMap().put(k1(), v1());
    expectAdded(e0(), e1());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ONE)
  public void testForcePutKeyPresent() {
    getMap().forcePut(k0(), v1());
    expectContents(Helpers.mapEntry(k0(), v1()));

        ImmutableMultimap.<Integer, Object>of(
            0, unhashables.e0(), 2, "hey you", 0, unhashables.e1());
    assertEquals(2, multimap.get(0).size());
    assertTrue(multimap.get(0).contains(unhashables.e0()));
    assertTrue(multimap.get(0).contains(unhashables.e1()));
    assertTrue(multimap.get(2).contains("hey you"));
  }

  public void testEquals() {
    new EqualsTester()

  protected final K k0() {
    return e0().getKey();
  }

  protected final V v0() {
    return e0().getValue();
  }

  protected final K k1() {
    return e1().getKey();
  }

  protected final V v1() {
    return e1().getValue();
  }

  protected final K k2() {
    return e2().getKey();
  }

  protected final V v2() {
    return e2().getValue();
  }

  protected final K k0() {
    return e0().getKey();
  }

  protected final V v0() {
    return e0().getValue();
  }

  protected final K k1() {
    return e1().getKey();
  }

  protected final V v1() {
    return e1().getValue();
  }

  protected final K k2() {
    return e2().getKey();
  }

  protected final V v2() {
    return e2().getValue();
  }

  }

  public static <E> ImmutableList<E> of(E e1, E e2, E e3, E e4, E e5) {
    return new RegularImmutableList<E>(ImmutableList.<E>nullCheckedList(e1, e2, e3, e4, e5));
  }

  public static <E> ImmutableList<E> of(E e1, E e2, E e3, E e4, E e5, E e6) {
    return new RegularImmutableList<E>(ImmutableList.<E>nullCheckedList(e1, e2, e3, e4, e5, e6));
  }

  }

  @Override
  protected Map<Object, Integer> makePopulatedMap() {
    Colliders colliders = new Colliders();
    return ImmutableMap.of(
        colliders.e0(), 0,
        colliders.e1(), 1,
        colliders.e2(), 2,
        colliders.e3(), 3);
  }

  @Override
  protected Object getKeyNotInPopulatedMap() {
    return new Colliders().e4();
  }

  @Override

  protected abstract <E extends Comparable<? super E>> Set<E> of(E e1, E e2, E e3);

  protected abstract <E extends Comparable<? super E>> Set<E> of(E e1, E e2, E e3, E e4);

  protected abstract <E extends Comparable<? super E>> Set<E> of(E e1, E e2, E e3, E e4, E e5);

  protected abstract <E extends Comparable<? super E>> Set<E> of(
      E e1, E e2, E e3, E e4, E e5, E e6, E... rest);

  protected abstract <E extends Comparable<? super E>> Set<E> of(E e1, E e2, E e3);

  protected abstract <E extends Comparable<? super E>> Set<E> of(E e1, E e2, E e3, E e4);

  protected abstract <E extends Comparable<? super E>> Set<E> of(E e1, E e2, E e3, E e4, E e5);

  protected abstract <E extends Comparable<? super E>> Set<E> of(
      E e1, E e2, E e3, E e4, E e5, E e6, E... rest);

    @Override
    public SampleElements<Entry<V, K>> samples() {
      SampleElements<Entry<K, V>> samples = generator.samples();
      return new SampleElements<>(
          reverse(samples.e0()),
          reverse(samples.e1()),
          reverse(samples.e2()),
          reverse(samples.e3()),
          reverse(samples.e4()));
    }

    private Entry<V, K> reverse(Entry<K, V> entry) {