toMap(keyFunction, valueFunction, mergeFunction, LinkedHashMap::new), ImmutableMap::copyOf);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
          Comparator<? super K> comparator,
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    checkNotNull(comparator);

  }

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

  public static <T extends @Nullable Object, K, V>