}
  }

  /** The inverse of any other {@code AbstractBiMap} subclass. */
  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractBiMap<K, V> {
    Inverse(Map<K, V> backward, AbstractBiMap<V, K> forward) {
      super(backward, forward);
    }

    /*
     * Serialization stores the forward bimap, the inverse of this inverse.

    }
  }

  /** The inverse of any other {@code AbstractBiMap} subclass. */
  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractBiMap<K, V> {
    Inverse(Map<K, V> backward, AbstractBiMap<V, K> forward) {
      super(backward, forward);
    }

    /*
     * Serialization stores the forward bimap, the inverse of this inverse.