*       instance is unsafely published.
   * </ul>
   */
  private transient @Nullable ConcurrentHashMultiset<E> deserializationReplacement;

  /**
   * Creates a new, empty {@code ConcurrentHashMultiset} using the default initial capacity, load
   * factor, and concurrency settings.
   */
  public static <E> ConcurrentHashMultiset<E> create() {
    return create(new ConcurrentHashMap<>());
  }

  /**

    private final ContainsMultiset a;
    private final ConcurrentHashMultiset<?> z;

    ContainsBothWithContainsMultisetFirst(ContainsMultiset a, ConcurrentHashMultiset<?> z) {
      this.a = a;
      this.z = z;
    }
  }

  public void testCreate() {
    ConcurrentHashMultiset<Integer> multiset = ConcurrentHashMultiset.create();
    assertTrue(multiset.isEmpty());
    reserializeAndAssert(multiset);

    testAddAndRemove(mapMaker.makeMap());
  }

  private void testAddAndRemove(ConcurrentMap<String, AtomicInteger> map)
      throws ExecutionException, InterruptedException {

    ConcurrentHashMultiset<String> multiset = ConcurrentHashMultiset.create(map);
    int nThreads = 20;
    int tasksPerThread = 10;
    int nTasks = nThreads * tasksPerThread;
    ExecutorService pool = newFixedThreadPool(nThreads);

   * is used only by those methods, and it is never set in a "normal" instance.
   *
   * <p>For more background, see {@code ConcurrentHashMultiset.deserializationReplacement}.
   */
  private transient @Nullable TreeMultiset<E> deserializationReplacement;

  TreeMultiset(Reference<AvlNode<E>> rootReference, GeneralRange<E> range, AvlNode<E> endLink) {

   * is used only by those methods, and it is never set in a "normal" instance.
   *
   * <p>For more background, see {@code ConcurrentHashMultiset.deserializationReplacement}.
   */
  private transient @Nullable TreeMultiset<E> deserializationReplacement;

  TreeMultiset(Reference<AvlNode<E>> rootReference, GeneralRange<E> range, AvlNode<E> endLink) {