import org.jspecify.annotations.Nullable;

/** Collectors utilities for {@code common.collect} internals. */
@GwtCompatible
@IgnoreJRERequirement // used only from APIs with Java 8 types in them
final class CollectCollectors {

  private static final Collector<Object, ?, ImmutableList<Object>> TO_IMMUTABLE_LIST =
      Collector.of(
          ImmutableList::builder,
          ImmutableList.Builder::add,

import java.util.stream.Collector;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/** Collectors utilities for {@code common.collect} internals. */
@GwtCompatible
final class CollectCollectors {

  private static final Collector<Object, ?, ImmutableList<Object>> TO_IMMUTABLE_LIST =
      Collector.of(
          ImmutableList::builder,
          ImmutableList.Builder::add,

      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableSortedMap(Ordering.natural(), keyFunction, valueFunction);
  }

  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(

   * encounter order.
   *
   * @since 21.0
   */
  public static <E> Collector<E, ?, ImmutableMultiset<E>> toImmutableMultiset() {
    return CollectCollectors.toImmutableMultiset(Function.identity(), e -> 1);
  }

  /**
   * Returns a {@code Collector} that accumulates elements into an {@code ImmutableMultiset} whose

   */
  @IgnoreJRERequirement // Users will use this only if they're already using streams.
  public static <E> Collector<E, ?, ImmutableMultiset<E>> toImmutableMultiset() {
    return CollectCollectors.toImmutableMultiset(Function.identity(), e -> 1);
  }

  /**
   * Returns a {@code Collector} that accumulates elements into an {@code ImmutableMultiset} whose

      Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableListMultimap(keyFunction, valueFunction);
  }

  /**
   * Returns a {@code Collector} accumulating entries into an {@code ImmutableListMultimap}. Each

      Collector<T, ?, ImmutableRangeMap<K, V>> toImmutableRangeMap(
          Function<? super T, Range<K>> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableRangeMap(keyFunction, valueFunction);
  }

  /**
   * Returns an empty immutable range map.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */

      Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableListMultimap(keyFunction, valueFunction);
  }

  /**
   * Returns a {@code Collector} accumulating entries into an {@code ImmutableListMultimap}. Each

      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableSetMultimap(keyFunction, valueFunction);
  }

  /**
   * Returns a {@code Collector} accumulating entries into an {@code ImmutableSetMultimap}. Each

    }
  }

  public static <E> Collector<E, ?, ImmutableSortedSet<E>> toImmutableSortedSet(
      Comparator<? super E> comparator) {
    return CollectCollectors.toImmutableSortedSet(comparator);
  }

  @SuppressWarnings("unchecked")
  public static <E> ImmutableSortedSet<E> of() {
    return (ImmutableSortedSet<E>) NATURAL_EMPTY_SET;
  }