this.comparator = checkNotNull(comparator);
  }

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

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

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

  @Override

    ms.add("b", 2);
    SortedSet<String> elementSet = ms.elementSet();

    assertEquals("a", elementSet.first());
    assertEquals("c", elementSet.last());
    assertEquals(Ordering.natural(), elementSet.comparator());

    assertThat(elementSet.headSet("b")).containsExactly("a");
    assertThat(elementSet.tailSet("b")).containsExactly("b", "c").inOrder();
    assertThat(elementSet.subSet("a", "c")).containsExactly("a", "b").inOrder();

  @CanIgnoreReturnValue
  @Override
  public int remove(@Nullable Object element, int occurrences) {
    return delegate().remove(element, occurrences);
  }

  @Override
  public Set<E> elementSet() {
    return delegate().elementSet();
  }

  @Override
  public Set<Entry<E>> entrySet() {
    return delegate().entrySet();
  }

  @Override
  public boolean equals(@Nullable Object object) {

  /** A skeleton implementation for {@link SortedMultiset#elementSet}. */
  @SuppressWarnings("JdkObsolete") // TODO(b/6160855): Switch GWT emulations to NavigableSet.
  static class ElementSet<E extends @Nullable Object> extends Multisets.ElementSet<E>
      implements SortedSet<E> {
    @Weak private final SortedMultiset<E> multiset;

    ElementSet(SortedMultiset<E> multiset) {
      this.multiset = multiset;
    }

                      builder.addCopies(s, 2);
                    }
                    ImmutableSet<String> elementSet =
                        (ImmutableSet<String>) builder.build().elementSet();
                    return elementSet.asList();
                  }
                })
            .named("ImmutableMultiset.elementSet.asList")
            .withFeatures(
                CollectionSize.ANY,

  }

  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

    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;

  protected ForwardingSortedMultiset() {}

  @Override
  protected abstract SortedMultiset<E> delegate();

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

  /**
   * A sensible implementation of {@link SortedMultiset#elementSet} in terms of the following
   * methods: {@link SortedMultiset#clear}, {@link SortedMultiset#comparator}, {@link

  }

  @Override
  public int size() {
    return size;
  }

  @Override
  public ImmutableSet<E> elementSet() {
    ImmutableSet<E> result = elementSet;
    return (result == null) ? elementSet = new ElementSet() : result;
  }

  @WeakOuter
  private final class ElementSet extends IndexedImmutableSet<E> {

    @Override
    E get(int index) {
      return contents.getKey(index);
    }

    ms.add("b", 2);
    ms.add("c");
    assertThat(ms.elementSet()).containsExactly("a", "b", "c").inOrder();
    ms.remove("b");
    assertThat(ms.elementSet()).containsExactly("a", "b", "c").inOrder();
    ms.add("b");
    assertThat(ms.elementSet()).containsExactly("a", "b", "c").inOrder();
    ms.remove("b", 2);
    ms.add("b");
    assertThat(ms.elementSet()).containsExactly("a", "c", "b").inOrder();
  }