public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
  }

  /**
   * Returns the empty bimap.
   *

  /**
   * Not supported. Use {@link #toImmutableBiMap} instead. This method exists only to hide {@link
   * ImmutableMap#toImmutableMap(Function, Function)} from consumers of {@code ImmutableBiMap}.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Use {@link ImmutableBiMap#toImmutableBiMap(Function, Function)}.
   */
  @Deprecated
  @DoNotCall("Use toImmutableBiMap")

    implements BiMap<K, V> {
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
  }

  // Casting to any type is safe because the set will never hold any elements.

        ImmutableSortedMap::copyOfSorted);
  }

  static <T extends @Nullable Object, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
      Function<? super T, ? extends K> keyFunction,
      Function<? super T, ? extends V> valueFunction) {
    checkNotNull(keyFunction);
    checkNotNull(valueFunction);
    return Collector.of(