return true;
    }

    @Override
    public Iterator<Entry<K, V>> iterator() {
      return entrySetIterator();
    }

    // See java.util.Collections.CheckedEntrySet for details on attacks.

    @Override
    public @Nullable Object[] toArray() {
      return standardToArray();
    }

    @Override
    @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures

      return true;
    }

    @Override
    public Iterator<Entry<K, V>> iterator() {
      return entrySetIterator();
    }

    // See java.util.Collections.CheckedEntrySet for details on attacks.

    @Override
    public @Nullable Object[] toArray() {
      return standardToArray();
    }

    @Override
    @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures

              return typePreservingCollection(entry.getValue(), mutex);
            }
          };
        }
      };
    }

    // See Collections.CheckedMap.CheckedEntrySet for details on attacks.

    @Override
    public @Nullable Object[] toArray() {
      synchronized (mutex) {
        /*
         * toArrayImpl returns `@Nullable Object[]` rather than `Object[]` but only because it can

      contents.add(checkNotNull(element), occurrences);
      return this;
    }

    /**
     * Adds or removes the necessary occurrences of an element such that the element attains the
     * desired count.
     *
     * @param element the element to add or remove occurrences of
     * @param count the desired count of the element in this multiset
     * @return this {@code Builder} object

   * the discussion in the {@link #addListener} documentation. All its warnings about heavyweight
   * listeners are also applicable to heavyweight callbacks passed to this method.
   *
   * <p>For a more general interface to attach a completion listener, see {@link #addListener}.
   *
   * <p>This method is similar to {@link java.util.concurrent.CompletableFuture#whenComplete} and

 * passing in unsanitized user data then a malicious user could force it. A light shuffle of the
 * data using an unpredictable seed should normally be enough to thwart this attack.
 *
 * <p>The time taken to compute multiple quantiles on the same dataset using {@link Scale#indexes
 * indexes} is generally less than the total time taken to compute each of them separately, and

  @CheckForNull private transient Node<K, V> tail; // the tail for all keys
  private transient Map<K, KeyList<K, V>> keyToKeyList;
  private transient int size;

  /*
   * Tracks modifications to keyToKeyList so that addition or removal of keys invalidates
   * preexisting iterators. This does *not* track simple additions and removals of values

  final Policy policy;

  private CycleDetectingLockFactory(Policy policy) {
    this.policy = checkNotNull(policy);
  }

  /**
   * Tracks the currently acquired locks for each Thread, kept up to date by calls to {@link
   * #aboutToAcquire(CycleDetectingLock)} and {@link #lockStateChanged(CycleDetectingLock)}.
   */

  /**
   * The input futures. After {@link #init}, this field is read only by {@link #afterDone()} (to
   * propagate cancellation) and {@link #toString()}. To access the futures' <i>values</i>, {@code
   * AggregateFuture} attaches listeners that hold references to one or more inputs. And in the case
   * of {@link CombinedFuture}, the user-supplied callback usually has its own references to inputs.
   */
  /*

      Cell[] as;
      Cell a;
      int n;
      long v;
      if ((as = cells) != null && (n = as.length) > 0) {
        if ((a = as[(n - 1) & h]) == null) {
          if (busy == 0) { // Try to attach new Cell
            Cell r = new Cell(x); // Optimistically create
            if (busy == 0 && casBusy()) {
              boolean created = false;
              try { // Recheck under lock
                Cell[] rs;