@VisibleForTesting @CheckForNull transient @Nullable Object[] elements;

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   */
  private transient int metadata;

   *
   * <p>This class is accessible but not supported in GWT as it references {@link
   * PermittedMetaException}.
   */
  protected final class MultiExceptionListIterator implements ListIterator<E> {
    // TODO: track seen elements when order isn't guaranteed
    // TODO: verify contents afterward
    // TODO: something shiny and new instead of Stack
    // TODO: test whether null is supported (create a Feature)
    /**

  }

  /**
   * A {@code LockGraphNode} associated with each lock instance keeps track of the directed edges in
   * the lock acquisition graph.
   */
  private static class LockGraphNode {

    /**
     * The map tracking the locks that are known to be acquired before this lock, each associated
     * with an example stack trace. Locks are weakly keyed to allow proper garbage collection when
     * they are no longer referenced.

  Set<V> createCollection() {
    return Platform.newLinkedHashSetWithExpectedSize(valueSetCapacity);
  }

  /**
   * {@inheritDoc}
   *
   * <p>Creates a decorated insertion-ordered set that also keeps track of the order in which
   * key-value pairs are added to the multimap.
   *
   * @param key key to associate with values in the collection
   * @return a new decorated set containing a collection of values for one key

    // NOTE: If we ever want to use a custom executor here, have a look at CombinedFuture as we'll
    // need to handle RejectedExecutionException

    if (allMustSucceed) {
      // We need fail fast, so we have to keep track of which future failed so we can propagate
      // the exception immediately

      // Register a listener on each Future in the list to update the state of this future.

  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
   * that are not the first to be added or last to be removed for their key.
   */
  private transient int modCount;

   *
   * <p>This class is accessible but not supported in GWT as it references {@link
   * PermittedMetaException}.
   */
  protected final class MultiExceptionListIterator implements ListIterator<E> {
    // TODO: track seen elements when order isn't guaranteed
    // TODO: verify contents afterward
    // TODO: something shiny and new instead of Stack
    // TODO: test whether null is supported (create a Feature)
    /**

    movePivotToStartOfSlice(array, from, to);
    double pivot = array[from];

    // Move all elements with indexes in (from, to] which are greater than the pivot to the end of
    // the array. Keep track of where those elements begin.
    int partitionPoint = to;
    for (int i = to; i > from; i--) {
      if (array[i] > pivot) {
        swap(array, partitionPoint, i);
        partitionPoint--;
      }
    }

   * - System.nanoTime() is expensive enough that we want to call it the minimum required number of
   *   times, typically once before invoking a blocking method. This often requires keeping track of
   *   the first time in a method that nanoTime() has been invoked, for which the special value 0L
   *   is reserved to mean "uninitialized". If timeout is non-positive, then nanoTime need never be
   *   called.

   * href="https://github.com/google/guava/wiki/GraphsExplained#non-recursiveness">recursively</a>.
   * This is because the {@code forTree()}-based implementations don't keep track of visited nodes,
   * and therefore don't need to call `equals()` or `hashCode()` on the node objects; this saves
   * both time and space versus traversing the same graph using {@code forGraph()}.
   *