return oldValue;
    }
  }

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

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

  private static final class Inverse<K extends @Nullable Object, V extends @Nullable Object>

    assertEquals(HashBiMap.create(), bimap);
    bimap.put(Currency.DOLLAR, "dollar");
    assertThat(bimap.get(Currency.DOLLAR)).isEqualTo("dollar");
    assertEquals(Currency.DOLLAR, bimap.inverse().get("dollar"));
  }

  public void testCreateFromMap() {
    /* Test with non-empty Map. */
    Map<Currency, String> map =
        ImmutableMap.of(
            Currency.DOLLAR, "dollar",

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

        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(),

    if (!parentBuilder.getFeatures().contains(NoRecurse.INVERSE)) {
      derived.add(
          BiMapTestSuiteBuilder.using(
                  new InverseBiMapGenerator<K, V>(parentBuilder.getSubjectGenerator()))
              .withFeatures(computeInverseFeatures(parentBuilder.getFeatures()))
              .named(parentBuilder.getName() + " inverse")
              .suppressing(parentBuilder.getSuppressedTests())

    /* No aliasing on inverse operations. */
    assertThat(unmod.inverse()).isSameInstanceAs(unmod.inverse());
    assertThat(unmod.inverse().inverse()).isSameInstanceAs(unmod);

    /* Unmodifiable is a view. */
    mod.put(4, "four");
    assertEquals(true, unmod.get(4).equals("four"));
    assertEquals(true, unmod.inverse().get("four").equals(4));

    iterator.next();
    iterator.next();
    iterator.remove();
    iterator.next();
    iterator.remove();
    assertEquals(1, bimap.size());
    assertEquals(1, bimap.inverse().size());
  }

  @SuppressWarnings("IdentityHashMapBoxing") // explicitly testing IdentityHashMap
  public void testIdentityEntrySetIteratorRemove() {
    BiMap<Integer, String> bimap =

    iterator.next();
    iterator.next();
    iterator.remove();
    iterator.next();
    iterator.remove();
    assertEquals(1, bimap.size());
    assertEquals(1, bimap.inverse().size());
  }

  @SuppressWarnings("IdentityHashMapBoxing") // explicitly testing IdentityHashMap
  public void testIdentityEntrySetIteratorRemove() {
    BiMap<Integer, String> bimap =

FIELD com.google.common.collect.ImmutableSet.asList
FIELD com.google.common.collect.JdkBackedImmutableBiMap.inverse
FIELD com.google.common.collect.Maps.FilteredMapValues.unfiltered
FIELD com.google.common.collect.Sets.SubSet.inputSet
FIELD com.google.common.collect.SingletonImmutableBiMap.inverse
FIELD com.google.common.collect.TreeTraverser.PostOrderNode.childIterator

    assertEquals(HashBiMap.create(), bimap);
    bimap.put(Currency.DOLLAR, "dollar");
    assertThat(bimap.get(Currency.DOLLAR)).isEqualTo("dollar");
    assertEquals(Currency.DOLLAR, bimap.inverse().get("dollar"));
  }

  public void testCreateFromMap() {
    /* Test with non-empty Map. */
    Map<Currency, String> map =
        ImmutableMap.of(
            Currency.DOLLAR, "dollar",