* 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");

  abstract SortedMultiset<E> forwardMultiset();

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

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

  // Sorting of user-defined classes

  @Test
  public void customComparator() {
    Comparator<NonComparableSuperClass> comparator =
        new Comparator<NonComparableSuperClass>() {
          @Override
          public int compare(NonComparableSuperClass left, NonComparableSuperClass right) {
            return left.value.compareTo(right.value);
          }
        };

    MutableGraph<NonComparableSuperClass> graph =

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

  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) {
              return ((Comparable) o1).compareTo(o2);
            }
          };
    }

      Comparator<? super T> comparator, @ParametricNullness T endpoint, BoundType boundType) {
    return new GeneralRange<>(comparator, true, endpoint, boundType, false, null, OPEN);
  }

  /**
   * Returns everything below the endpoint relative to the specified comparator, with the specified
   * endpoint behavior.
   */
  static <T extends @Nullable Object> GeneralRange<T> upTo(

   *   <li>SORTED: ordering according to a supplied comparator is guaranteed.
   * </ul>
   */
  public enum Type {
    UNORDERED,
    STABLE,
    INSERTION,
    SORTED
  }

  private ElementOrder(Type type, @CheckForNull Comparator<T> comparator) {
    this.type = checkNotNull(type);
    this.comparator = comparator;
    checkState((type == Type.SORTED) == (comparator != null));
  }

   *   <li>SORTED: ordering according to a supplied comparator is guaranteed.
   * </ul>
   */
  public enum Type {
    UNORDERED,
    STABLE,
    INSERTION,
    SORTED
  }

  private ElementOrder(Type type, @CheckForNull Comparator<T> comparator) {
    this.type = checkNotNull(type);
    this.comparator = comparator;
    checkState((type == Type.SORTED) == (comparator != null));
  }

    this.comparator = checkNotNull(comparator);
  }

  @Override
  public int compare(@ParametricNullness T a, @ParametricNullness T b) {
    return comparator.compare(a, b);
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    if (object == this) {
      return true;
    }
    if (object instanceof ComparatorOrdering) {
      ComparatorOrdering<?> that = (ComparatorOrdering<?>) object;