* Deserialization calls inverse() on the forward bimap and returns that
     * inverse.
     *
     * If a bimap and its inverse are serialized together, the deserialized
     * instances have inverse() methods that return the other.
     */

    @Override
    @ParametricNullness
    K checkKey(@ParametricNullness K key) {
      return inverse.checkValue(key);
    }

     * Deserialization calls inverse() on the forward bimap and returns that
     * inverse.
     *
     * If a bimap and its inverse are serialized together, the deserialized
     * instances have inverse() methods that return the other.
     */

    @Override
    @ParametricNullness
    K checkKey(@ParametricNullness K key) {
      return inverse.checkValue(key);
    }