* 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;

  /** The number of elements contained in the set. */
  private transient int size;

  /** Constructs a new empty instance of {@code CompactHashSet}. */

   * 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;

  /** The number of elements contained in the set. */
  private transient int size;

  /** Constructs a new empty instance of {@code CompactHashSet}. */