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();

    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()));

 * to ensure binary compatibility with older Guava versions that specified {@code elementSet()} to
 * return {@code SortedSet}.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
interface SortedMultisetBridge<E extends @Nullable Object> extends Multiset<E> {
  @Override
  SortedSet<E> elementSet();

  @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() {

    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();

    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()));

  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

  @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) {

    this.length = 0;
  }

  RegularImmutableSortedMultiset(
      RegularImmutableSortedSet<E> elementSet, long[] cumulativeCounts, int offset, int length) {
    this.elementSet = elementSet;
    this.cumulativeCounts = cumulativeCounts;
    this.offset = offset;
    this.length = length;
  }

  private int getCount(int index) {
    return (int) (cumulativeCounts[offset + index + 1] - cumulativeCounts[offset + index]);
  }

  @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() {