* @since 14.0
   */
  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
  public final <K> ImmutableMap<K, @NonNull E> uniqueIndex(Function<? super E, K> keyFunction) {
    return Maps.uniqueIndex((Iterable<@NonNull E>) getDelegate(), keyFunction);
  }

  /**
   * Returns an array containing all of the elements from this fluent iterable in iteration order.
   *

   * @since 14.0
   */
  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
  public final <K> ImmutableMap<K, @NonNull E> uniqueIndex(Function<? super E, K> keyFunction) {
    return Maps.uniqueIndex((Iterable<@NonNull E>) getDelegate(), keyFunction);
  }

  /**
   * Returns an array containing all of the elements from this fluent iterable in iteration order.
   *

    ImmutableMap<Integer, String> outputMap =
        Maps.uniqueIndex(INT_TO_STRING_MAP.values(), Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  public void testUniqueIndexIterable() {
    ImmutableMap<Integer, String> outputMap =
        Maps.uniqueIndex(
            new Iterable<String>() {
              @Override