return keyToIndex().keySet().asList().get(index);
    }

    @CheckForNull
    abstract V getValue(int keyIndex);

    @Override
    ImmutableSet<K> createKeySet() {
      return isFull() ? keyToIndex().keySet() : super.createKeySet();
    }

    @Override
    public int size() {
      return size;
    }

    @Override
    @CheckForNull
    public V get(@CheckForNull Object key) {

    throw new AssertionError("should never be called");
  }

  @Override
  Map<K, Collection<V>> createAsMap() {
    return new AsMap();
  }

  @Override
  Set<K> createKeySet() {
    return asMap().keySet();
  }

  boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
    Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();

    return false;
  }

  @Override
  ImmutableSet<Entry<K, V>> createEntrySet() {
    return ImmutableSet.of(immutableEntry(singleKey, singleValue));
  }

  @Override
  ImmutableSet<K> createKeySet() {
    return ImmutableSet.of(singleKey);
  }

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

    throw new AssertionError("should never be called");
  }

  @Override
  Map<K, Collection<V>> createAsMap() {
    return new AsMap();
  }

  @Override
  Set<K> createKeySet() {
    return asMap().keySet();
  }

  boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
    Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();

    return isEmpty()
        ? ImmutableSet.<Entry<K, V>>of()
        : new ImmutableMapEntrySet.RegularEntrySet<K, V>(this, entries);
  }

  @Override
  ImmutableSet<K> createKeySet() {
    return new ImmutableMapKeySet<>(this);
  }

  @Override
  public void forEach(BiConsumer<? super K, ? super V> action) {
    checkNotNull(action);
    for (Entry<K, V> entry : entries) {

      return keyToIndex().keySet().asList().get(index);
    }

    @CheckForNull
    abstract V getValue(int keyIndex);

    @Override
    ImmutableSet<K> createKeySet() {
      return isFull() ? keyToIndex().keySet() : super.createKeySet();
    }

    @Override
    public int size() {
      return size;
    }

    @Override
    @CheckForNull
    public V get(@CheckForNull Object key) {

      return emptySet();
    } else {
      return emptyList();
    }
  }

  @Override
  public void clear() {
    keySet().clear();
  }

  @Override
  Set<K> createKeySet() {
    return Sets.filter(unfiltered.keySet(), keyPredicate);
  }

  @Override
  public Collection<V> get(@ParametricNullness K key) {
    if (keyPredicate.apply(key)) {
      return unfiltered.get(key);

    ImmutableSet<K> result = keySet;
    return (result == null) ? keySet = createKeySet() : result;
  }

  /*
   * This could have a good default implementation of return new ImmutableKeySet<K, V>(this),
   * but ProGuard can't figure out how to eliminate that default when RegularImmutableMap
   * overrides it.
   */
  abstract ImmutableSet<K> createKeySet();

  UnmodifiableIterator<K> keyIterator() {

    ImmutableSet<K> result = keySet;
    return (result == null) ? keySet = createKeySet() : result;
  }

  /*
   * This could have a good default implementation of return new ImmutableKeySet<K, V>(this),
   * but ProGuard can't figure out how to eliminate that default when RegularImmutableMap
   * overrides it.
   */
  abstract ImmutableSet<K> createKeySet();

  UnmodifiableIterator<K> keyIterator() {

    return false;
  }

  @Override
  ImmutableSet<Entry<K, V>> createEntrySet() {
    return new ImmutableMapEntrySet.RegularEntrySet<>(this, entries);
  }

  @Override
  ImmutableSet<K> createKeySet() {
    return new KeySet<>(this);
  }

  @GwtCompatible(emulated = true)
  private static final class KeySet<K> extends IndexedImmutableSet<K> {
    private final RegularImmutableMap<K, ?> map;