assertEquals("one", copy.inverse().get(1));
    assertSame(copy, copy.inverse().inverse());
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testInverseSerialization() {
    ImmutableBiMap<String, Integer> bimap =
        ImmutableBiMap.copyOf(ImmutableMap.of(1, "one", 2, "two")).inverse();

    }
  }

  /** The inverse of any other {@code AbstractBiMap} subclass. */
  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractBiMap<K, V> {
    Inverse(Map<K, V> backward, AbstractBiMap<V, K> forward) {
      super(backward, forward);
    }

    /*
     * Serialization stores the forward bimap, the inverse of this inverse.

        ImmutableListMultimap.<String, Integer>of().inverse());
    assertEquals(ImmutableListMultimap.of(1, "one"), ImmutableListMultimap.of("one", 1).inverse());
    assertEquals(
        ImmutableListMultimap.of(1, "one", 2, "two"),
        ImmutableListMultimap.of("one", 1, "two", 2).inverse());
    assertEquals(
        ImmutableListMultimap.of("of", 'o', "of", 'f', "to", 't', "to", 'o').inverse(),

        .inOrder();
    // backward map ordered by country
    assertThat(bimap.inverse().keySet())
        .containsExactly(Country.CANADA, Country.CHILE, Country.SWITZERLAND)
        .inOrder();
    // backward map ordered by country (even for currency values)
    assertThat(bimap.inverse().values())
        .containsExactly(Currency.DOLLAR, Currency.PESO, Currency.FRANC)
        .inOrder();
  }

    }
  }

  @LazyInit @RetainedWith @CheckForNull private transient BiMap<V, K> inverse;

  @Override
  public BiMap<V, K> inverse() {
    BiMap<V, K> result = inverse;
    return (result == null) ? inverse = new Inverse() : result;
  }

  private final class Inverse extends IteratorBasedAbstractMap<V, K>
      implements BiMap<V, K>, Serializable {
    BiMap<K, V> forward() {

  @LazyInit @RetainedWith @CheckForNull private transient ImmutableBiMap<V, K> inverse;

  @Override
  public ImmutableBiMap<V, K> inverse() {
    if (isEmpty()) {
      return ImmutableBiMap.of();
    }
    ImmutableBiMap<V, K> result = inverse;
    return (result == null) ? inverse = new Inverse() : result;
  }

  private final class Inverse extends ImmutableBiMap<V, K> {

    @Override
    public int size() {

      return oldValue;
    }
  }

  @LazyInit @RetainedWith @CheckForNull private transient BiMap<V, K> inverse;

  @Override
  public BiMap<V, K> inverse() {
    BiMap<V, K> result = inverse;
    return (result == null) ? inverse = new Inverse<K, V>(this) : result;
  }

  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractMap<V, K> implements BiMap<V, K>, Serializable {

        ImmutableListMultimap.<String, Integer>of().inverse());
    assertEquals(ImmutableListMultimap.of(1, "one"), ImmutableListMultimap.of("one", 1).inverse());
    assertEquals(
        ImmutableListMultimap.of(1, "one", 2, "two"),
        ImmutableListMultimap.of("one", 1, "two", 2).inverse());
    assertEquals(
        ImmutableListMultimap.of("of", 'o', "of", 'f', "to", 't', "to", 'o').inverse(),

  }

  public void testInverseMinimizesWork() {
    ImmutableSetMultimap<String, Character> multimap =
        ImmutableSetMultimap.of("of", 'o', "of", 'f', "to", 't', "to", 'o');
    assertSame(multimap.inverse(), multimap.inverse());
    assertSame(multimap, multimap.inverse().inverse());
  }

  private static <K, V> void assertMultimapEquals(

   *
   * @since 11.0
   */
  @Override
  public ImmutableListMultimap<V, K> inverse() {
    ImmutableListMultimap<V, K> result = inverse;
    return (result == null) ? (inverse = invert()) : result;
  }

  private ImmutableListMultimap<V, K> invert() {
    Builder<V, K> builder = builder();
    for (Entry<K, V> entry : entries()) {
      builder.put(entry.getValue(), entry.getKey());
    }