}

  private final class KeySet extends View<K, V, K> {
    KeySet() {
      super(HashBiMap.this);
    }

    @Override
    @ParametricNullness
    K forEntry(int entry) {
      // The cast is safe because we call forEntry only for indexes that contain entries.
      return uncheckedCastNullableTToT(keys[entry]);
    }

    @Override
    public boolean contains(@Nullable Object o) {