*/
    abstract E castForTesting(InternalEntry<K, V, ?> entry);

    /** Unsafely extracts the key reference queue used by this segment. */
    ReferenceQueue<K> getKeyReferenceQueueForTesting() {
      throw new AssertionError();
    }

    /** Unsafely extracts the value reference queue used by this segment. */
    ReferenceQueue<V> getValueReferenceQueueForTesting() {

     */
    abstract E castForTesting(InternalEntry<K, V, ?> entry);

    /** Unsafely extracts the key reference queue used by this segment. */
    ReferenceQueue<K> getKeyReferenceQueueForTesting() {
      throw new AssertionError();
    }

    /** Unsafely extracts the value reference queue used by this segment. */
    ReferenceQueue<V> getValueReferenceQueueForTesting() {

   *       directly during deserialization. However, we would lose Java's guarantees for {@code
   *       final} fields, including that their values are guaranteed to be visible even when an
   *       instance is unsafely published.
   * </ul>
   */
  private transient @Nullable ConcurrentHashMultiset<E> deserializationReplacement;

  /**
   * Creates a new, empty {@code ConcurrentHashMultiset} using the default initial capacity, load

      new AtomicReference<>(immediateVoidFuture());

  @LazyInit private ThreadConfinedTaskQueue latestTaskQueue = new ThreadConfinedTaskQueue();

  /**
   * This object is unsafely published, but avoids problematic races by relying exclusively on the
   * identity equality of its Thread field so that the task field is only accessed by a single
   * thread.
   */