builder.put(elements[i], i);
      }
      return builder.build().keySet().asList();
    }

    @Override
    public List<String> order(List<String> insertionOrder) {
      return Ordering.<String>natural().sortedCopy(insertionOrder);
    }
  }

  public static class ImmutableSortedMapValueListGenerator extends TestStringListGenerator {
    @Override
    protected List<String> create(String[] elements) {

          Comparator<? super E> comparator = spliterator.getComparator();
          if (comparator == null) {
            // A sorted spliterator with no comparator is already using natural order.
            // (We could probably find a way to avoid rawtypes here if we wanted.)
            @SuppressWarnings({"unchecked", "rawtypes"})
            Comparator<? super E> naturalOrder =

          Comparator<? super E> comparator = spliterator.getComparator();
          if (comparator == null) {
            // A sorted spliterator with no comparator is already using natural order.
            // (We could probably find a way to avoid rawtypes here if we wanted.)
            @SuppressWarnings({"unchecked", "rawtypes"})
            Comparator<? super E> naturalOrder =

   *
   * <p>An empty iterable has only one permutation, which is an empty list.
   *
   * <p>This method is equivalent to {@code Collections2.orderedPermutations(list,
   * Ordering.natural())}.
   *
   * @param elements the original iterable whose elements have to be permuted.
   * @return an immutable {@link Collection} containing all the different permutations of the
   *     original iterable.

import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import org.jspecify.annotations.Nullable;

/**
 * Implementation of {@code Table} whose iteration ordering across row keys is sorted by their
 * natural ordering or by a supplied comparator. Note that iterations across the columns keys for a
 * single row key may or may not be ordered, depending on the implementation. When rows and columns

   */
  @Override
  Map<K, Collection<V>> asMap();

  /**
   * Returns the comparator that orders the multimap values, with {@code null} indicating that
   * natural ordering is used.
   */
  @Nullable Comparator<? super V> valueComparator();

  }

  public void testOrderedPermutationSetRepeatedElements() {
    List<Integer> list = newArrayList(1, 1, 2, 2);
    Iterator<List<Integer>> permutations =
        Collections2.orderedPermutations(list, Ordering.natural()).iterator();

    assertNextPermutation(newArrayList(1, 1, 2, 2), permutations);
    assertNextPermutation(newArrayList(1, 2, 1, 2), permutations);
    assertNextPermutation(newArrayList(1, 2, 2, 1), permutations);

    private final SortedSet<String> delegate = Sets.newTreeSet(Ordering.natural());

    @Override
    protected SortedSet<String> delegate() {
      return delegate;
    }
  }

  private static class NonNavigableSortedMap extends ForwardingSortedMap<String, String> {

    private final SortedMap<String, String> delegate = new SafeTreeMap<>(Ordering.natural());

    @Override

 * signature doesn't say so explicitly, the map returned by {@link #asMap} has {@code Set} values.
 *
 * <p>If the values corresponding to a single key should be ordered according to a {@link
 * java.util.Comparator} (or the natural order), see the {@link SortedSetMultimap} subinterface.
 *
 * <p>Since the value collections are sets, the behavior of a {@code SetMultimap} is not specified

 * signature doesn't say so explicitly, the map returned by {@link #asMap} has {@code Set} values.
 *
 * <p>If the values corresponding to a single key should be ordered according to a {@link
 * java.util.Comparator} (or the natural order), see the {@link SortedSetMultimap} subinterface.
 *
 * <p>Since the value collections are sets, the behavior of a {@code SetMultimap} is not specified