}

  @Override
  public void clear() {
    delegate.clear();
  }

  @Override
  public Comparator<? super K> comparator() {
    Comparator<? super K> comparator = delegate.comparator();
    if (comparator != null) {
      return comparator;
    }
    return NATURAL_ORDER;
  }

  @Override
  public boolean containsKey(Object key) {
    try {

  abstract SortedMultiset<E> forwardMultiset();

  @LazyInit private transient @Nullable Comparator<? super E> comparator;

  @Override
  public Comparator<? super E> comparator() {
    Comparator<? super E> result = comparator;
    if (result == null) {
      result = Ordering.from(forwardMultiset().comparator()).reverse();
      comparator = result;
    }
    return result;
  }

    assertThat(elementSet.last()).isEqualTo("a");
    assertEquals(comparator, elementSet.comparator());
  }

  public void testNullAcceptingComparator() throws Exception {
    Comparator<@Nullable String> comparator = Ordering.<String>natural().<String>nullsFirst();
    TreeMultiset<@Nullable String> ms = TreeMultiset.create(comparator);

    ms.add("b");
    ms.add(null);
    ms.add("a");
    ms.add("b");

    Ordering<@Nullable Object> comparator = Ordering.allEqual();
    assertThat(comparator.reverse()).isSameInstanceAs(comparator);

    assertEquals(0, comparator.compare(null, null));
    assertEquals(0, comparator.compare(new Object(), new Object()));
    assertEquals(0, comparator.compare("apples", "oranges"));
    assertThat(reserialize(comparator)).isSameInstanceAs(comparator);

    Ordering<@Nullable Object> comparator = Ordering.allEqual();
    assertThat(comparator.reverse()).isSameInstanceAs(comparator);

    assertEquals(0, comparator.compare(null, null));
    assertEquals(0, comparator.compare(new Object(), new Object()));
    assertEquals(0, comparator.compare("apples", "oranges"));
    assertThat(reserialize(comparator)).isSameInstanceAs(comparator);

    @Override
    protected List<String> create(String[] elements) {
      Comparator<String> comparator = createExplicitComparator(elements);
      ImmutableSet<String> set = ImmutableSortedSet.copyOf(comparator, asList(elements));
      return set.asList();
    }
  }

  private final transient long[] cumulativeCounts;
  private final transient int offset;
  private final transient int length;

  RegularImmutableSortedMultiset(Comparator<? super E> comparator) {
    this.elementSet = ImmutableSortedSet.emptySet(comparator);
    this.cumulativeCounts = zeroCumulativeCounts;
    this.offset = 0;
    this.length = 0;
  }

  RegularImmutableSortedMultiset(

    implements SortedMultiset<E> {
  private final Comparator<? super E> comparator;

  // needed for serialization
  @SuppressWarnings("unchecked")
  AbstractSortedMultiset() {
    this((Comparator) Ordering.natural());
  }

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

  @Override
  public SortedSet<E> elementSet() {

  Comparator<Object> unsafeComparator() {
    return (Comparator<Object>) comparator;
  }

  RegularImmutableSortedSet<E> getSubSet(int newFromIndex, int newToIndex) {
    if (newFromIndex == 0 && newToIndex == size()) {
      return this;
    } else if (newFromIndex < newToIndex) {
      return new RegularImmutableSortedSet<>(
          elements.subList(newFromIndex, newToIndex), comparator);
    } else {

                new TestStringSortedMapGenerator() {
                  private final Comparator<String> comparator = NullsBeforeTwo.INSTANCE;

                  @Override
                  protected SortedMap<String, String> create(Entry<String, String>[] entries) {
                    SortedMap<String, String> map = new SafeTreeMap<>(comparator);
                    for (Entry<String, String> entry : entries) {