}

    @Override
    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
      return new NavigableElementSet<>(
          multiset().headMultiset(toElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
      return new NavigableElementSet<>(

    }
  }

  @GwtIncompatible // NavigableSet
  private static final class FilteredNavigableSet<E extends @Nullable Object>
      extends FilteredSortedSet<E> implements NavigableSet<E> {
    FilteredNavigableSet(NavigableSet<E> unfiltered, Predicate<? super E> predicate) {
      super(unfiltered, predicate);
    }

    NavigableSet<E> unfiltered() {
      return (NavigableSet<E>) unfiltered;
    }

        NavigableSet<Integer> filtered = filter(createUnfiltered(contents), EVEN);
        NavigableSet<Integer> unfiltered = createUnfiltered(filtered);

        assertEquals(unfiltered.pollLast(), filtered.pollLast());
        assertEquals(unfiltered, filtered);
      }
    }

    public void testNavigation() {
      for (List<Integer> contents : SAMPLE_INPUTS) {

  @WeakOuter
  final class WrappedNavigableSet extends WrappedSortedSet implements NavigableSet<V> {
    WrappedNavigableSet(
        @ParametricNullness K key, NavigableSet<V> delegate, @Nullable WrappedCollection ancestor) {
      super(key, delegate, ancestor);
    }

    @Override
    NavigableSet<V> getSortedSetDelegate() {
      return (NavigableSet<V>) super.getSortedSetDelegate();
    }

    @Override

  @Override
  public Comparator<? super E> comparator() {
    return delegate().comparator();
  }

  @Override
  NavigableSet<E> createElementSet() {
    return unmodifiableNavigableSet(delegate().elementSet());
  }

  @Override
  public NavigableSet<E> elementSet() {
    return (NavigableSet<E>) super.elementSet();
  }

  @LazyInit private transient @Nullable UnmodifiableSortedMultiset<E> descendingMultiset;

      Collection<E> collection) {
    if (collection instanceof NavigableSet) {
      return unmodifiableNavigableSet((NavigableSet<E>) collection);
    } else {
      return unmodifiableSortedSet((SortedSet<E>) collection);
    }
  }

  @Override
  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
    if (collection instanceof NavigableSet) {

  }

  AbstractSortedMultiset(Comparator<? super E> comparator) {
    this.comparator = checkNotNull(comparator);
  }

  @Override
  public NavigableSet<E> elementSet() {
    return (NavigableSet<E>) super.elementSet();
  }

  @Override
  NavigableSet<E> createElementSet() {
    return new SortedMultisets.NavigableElementSet<>(this);
  }

  @Override
  public Comparator<? super E> comparator() {

    @Override
    public NavigableMap<K, V> descendingMap() {
      return new StandardDescendingMap();
    }

    @Override
    public NavigableSet<K> navigableKeySet() {
      return new StandardNavigableKeySet();
    }

    @Override
    public NavigableSet<K> descendingKeySet() {
      return standardDescendingKeySet();
    }

    @Override
    public K firstKey() {
      return standardFirstKey();

  @Override
  int indexOf(@Nullable Object target) {
    return -1;
  }

  @Override
  public UnmodifiableIterator<C> iterator() {
    return emptyIterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return emptyIterator();
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override

      List<String> list = Lists.newArrayList(elements);
      list.add("\0");
      list.add("zzz");
      return ImmutableSortedSet.copyOf(list).subSet("\0\0", "zzy");
    }
  }

  @GwtIncompatible // NavigableSet
  public static class ImmutableSortedSetDescendingGenerator extends TestStringSortedSetGenerator {
    @Override
    protected SortedSet<String> create(String[] elements) {