}

  @CollectionSize.Require(absent = ZERO)
  public void testOrderedByComparator() {
    Comparator<? super K> comparator = navigableMap.comparator();
    if (comparator == null) {
      comparator =
          new Comparator<K>() {
            @SuppressWarnings("unchecked")
            @Override
            public int compare(K o1, K o2) {

  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;
  }

   * the given {@code comparator}.
   *
   * @see #testComparator(Comparator, List)
   */
  public static <T extends @Nullable Object> void testComparator(
      Comparator<? super T> comparator, T... valuesInExpectedOrder) {
    testComparator(comparator, asList(valuesInExpectedOrder));
  }

  /**

    assertEquals("a", elementSet.last());
    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");

   * the given {@code comparator}.
   *
   * @see #testComparator(Comparator, List)
   */
  public static <T extends @Nullable Object> void testComparator(
      Comparator<? super T> comparator, T... valuesInExpectedOrder) {
    testComparator(comparator, asList(valuesInExpectedOrder));
  }

  /**

    Ordering<@Nullable Object> comparator = Ordering.allEqual();
    assertSame(comparator, comparator.reverse());

    assertEquals(0, comparator.compare(null, null));
    assertEquals(0, comparator.compare(new Object(), new Object()));
    assertEquals(0, comparator.compare("apples", "oranges"));
    assertSame(comparator, reserialize(comparator));
    assertEquals("Ordering.allEqual()", comparator.toString());

    Ordering<@Nullable Object> comparator = Ordering.allEqual();
    assertSame(comparator, comparator.reverse());

    assertEquals(0, comparator.compare(null, null));
    assertEquals(0, comparator.compare(new Object(), new Object()));
    assertEquals(0, comparator.compare("apples", "oranges"));
    assertSame(comparator, reserialize(comparator));
    assertEquals("Ordering.allEqual()", comparator.toString());

    assertEquals("a", elementSet.last());
    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");

  /**
   * Returns the {@code Comparator} by which the elements of this iterable are ordered, or {@code
   * Ordering.natural()} if the elements are ordered by their natural ordering.
   */
  Comparator<? super T> comparator();

  /**
   * Returns an iterator over elements of type {@code T}. The elements are returned in nondecreasing
   * order according to the associated {@link #comparator}.
   */
  @Override

  /**
   * Returns the {@code Comparator} by which the elements of this iterable are ordered, or {@code
   * Ordering.natural()} if the elements are ordered by their natural ordering.
   */
  Comparator<? super T> comparator();

  /**
   * Returns an iterator over elements of type {@code T}. The elements are returned in nondecreasing
   * order according to the associated {@link #comparator}.
   */
  @Override