* @throws NullPointerException if {@code elements} or any of its contents is null
   * @since 15.0
   */
  public static <E> Set<E> newConcurrentHashSet(Iterable<? extends E> elements) {
    Set<E> set = newConcurrentHashSet();
    Iterables.addAll(set, elements);
    return set;
  }

  // LinkedHashSet

  /**
   * Creates a <i>mutable</i>, empty {@code LinkedHashSet} instance.

   * set is serializable.
   *
   * @return a new, empty thread-safe {@code Set}
   * @since 15.0
   */
  public static <E> Set<E> newConcurrentHashSet() {
    return Platform.newConcurrentHashSet();
  }

  /**
   * Creates a thread-safe set backed by a hash map and containing the given elements. The set is