}
        return valueSet;
      }
    }

    @Override
    @CheckForNull
    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
      synchronized (mutex) {
        return delegate().forcePut(key, value);
      }
    }

    @Override
    public BiMap<V, K> inverse() {
      synchronized (mutex) {

        }
        return valueSet;
      }
    }

    @Override
    @CheckForNull
    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
      synchronized (mutex) {
        return delegate().forcePut(key, value);
      }
    }

    @Override
    public BiMap<V, K> inverse() {
      synchronized (mutex) {

   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  @CheckForNull
  public final V forcePut(K key, V value) {
    throw new UnsupportedOperationException();
  }

  /**
   * Serialized type for all ImmutableBiMap instances. It captures the logical contents and they are

   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  @CheckForNull
  public final V forcePut(K key, V value) {
    throw new UnsupportedOperationException();
  }

  /**
   * Serialized type for all ImmutableBiMap instances. It captures the logical contents and they are

    BiMap<K, V> unfiltered() {
      return (BiMap<K, V>) unfiltered;
    }

    @Override
    @CheckForNull
    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
      checkArgument(apply(key, value));
      return unfiltered().forcePut(key, value);
    }

    @Override
    public BiMap<V, K> inverse() {
      return inverse;
    }

    @Override

    BiMap<K, V> unfiltered() {
      return (BiMap<K, V>) unfiltered;
    }

    @Override
    @CheckForNull
    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
      checkArgument(apply(key, value));
      return unfiltered().forcePut(key, value);
    }

    @Override
    public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
      unfiltered()

    try {
      unmod.put(4, "four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      unmod.forcePut(4, "four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      unmod.putAll(Collections.singletonMap(4, "four"));