}
      entriesUsed = true;
      return new RegularImmutableBiMap<K, V>(alternatingKeysAndValues, size);
    }

    /**
     * Throws {@link UnsupportedOperationException}. This method is inherited from {@link
     * ImmutableMap.Builder}, but it does not make sense for bimaps.
     *
     * @throws UnsupportedOperationException always

   */
  @Override
  public ImmutableSetMultimap<V, K> inverse() {
    ImmutableSetMultimap<V, K> result = inverse;
    return (result == null) ? (inverse = invert()) : result;
  }

  private ImmutableSetMultimap<V, K> invert() {
    Builder<V, K> builder = builder();
    for (Entry<K, V> entry : entries()) {
      builder.put(entry.getValue(), entry.getKey());
    }

   * @since 11.0
   */
  @Override
  public ImmutableListMultimap<V, K> inverse() {
    ImmutableListMultimap<V, K> result = inverse;
    return (result == null) ? (inverse = invert()) : result;
  }

  private ImmutableListMultimap<V, K> invert() {
    Builder<V, K> builder = builder();
    for (Entry<K, V> entry : entries()) {
      builder.put(entry.getValue(), entry.getKey());
    }