assertFalse(getMap().containsKey(k0()));

    assertTrue(getMap().containsKey(k1()));
    assertTrue(getMap().inverse().containsKey(null));
    assertNull(getMap().get(k1()));
    assertEquals(k1(), getMap().inverse().get(null));
    assertEquals(1, getMap().size());
  }

  // nb: inverse is run through its own entire suite

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ZERO)

    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();

    assertEquals("dollar", bimap.get("canada"));
    assertEquals("canada", bimap.inverse().get("dollar"));
  }

  private static final int N = 1000;

  public void testBashIt() throws Exception {
    BiMap<Integer, Integer> bimap = HashBiMap.create(N);
    BiMap<Integer, Integer> inverse = bimap.inverse();

    for (int i = 0; i < N; i++) {
      assertNull(bimap.put(2 * i, 2 * i + 1));
    }

    assertEquals("dollar", bimap.get("canada"));
    assertEquals("canada", bimap.inverse().get("dollar"));
  }

  private static final int N = 1000;

  public void testBashIt() throws Exception {
    BiMap<Integer, Integer> bimap = HashBiMap.create(N);
    BiMap<Integer, Integer> inverse = bimap.inverse();

    for (int i = 0; i < N; i++) {
      assertNull(bimap.put(2 * i, 2 * i + 1));
    }

    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())

  }

  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(

    /* No aliasing on inverse operations. */
    assertSame(unmod.inverse(), unmod.inverse());
    assertSame(unmod, unmod.inverse().inverse());

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

    /* No aliasing on inverse operations. */
    assertSame(unmod.inverse(), unmod.inverse());
    assertSame(unmod, unmod.inverse().inverse());

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

        return delegate().forcePut(key, value);
      }
    }

    @Override
    public BiMap<V, K> inverse() {
      synchronized (mutex) {
        if (inverse == null) {
          inverse = new SynchronizedBiMap<>(delegate().inverse(), mutex, this);
        }
        return inverse;
      }
    }

    private static final long serialVersionUID = 0;
  }

   *
   * @since 20.0
   */
  public abstract boolean canDecode(CharSequence chars);

  /**
   * Decodes the specified character sequence, and returns the resulting {@code byte[]}. This is the
   * inverse operation to {@link #encode(byte[])}.
   *
   * @throws IllegalArgumentException if the input is not a valid encoded string according to this
   *     encoding.
   */
  public final byte[] decode(CharSequence chars) {