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();

  @LazyInit @CheckForNull private transient Set<E> elementSet;

  @Override
  public Set<E> elementSet() {
    Set<E> result = elementSet;
    if (result == null) {
      elementSet = result = createElementSet();
    }
    return result;
  }

  /**
   * Creates a new instance of this multiset's element set, which will be returned by {@link
   * #elementSet()}.
   */
  Set<E> createElementSet() {

  }

  @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);
    }

  @CanIgnoreReturnValue
  @Override
  public int remove(@CheckForNull 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(@CheckForNull Object object) {

    return delegate().comparator();
  }

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

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

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

  @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();

      return (Multiset<E>) delegate;
    }

    @LazyInit @CheckForNull transient Set<E> elementSet;

    Set<E> createElementSet() {
      return Collections.<E>unmodifiableSet(delegate.elementSet());
    }

    @Override
    public Set<E> elementSet() {
      Set<E> es = elementSet;
      return (es == null) ? elementSet = createElementSet() : es;
    }

    Set<E> elementSet = getMultiset().elementSet();
    assertFalse(elementSet.contains(e3()));
    getMultiset().add(e3(), 4);
    assertTrue(elementSet.contains(e3()));
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testElementSetReflectsRemove() {
    Set<E> elementSet = getMultiset().elementSet();
    assertTrue(elementSet.contains(e0()));

    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();
  }

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