*
     * @param <E> the element type of {@link HashSet}
     * @return a new instance of {@link HashSet}
     * @see HashSet#HashSet()
     */
    public static <E> HashSet<E> newHashSet() {
        return new HashSet<>();
    }

    /**
     * Creates and returns a new instance of {@link HashSet}.
     *
     * @param <E> the element type of {@link HashSet}

  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call
  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) {
    return (elements instanceof Collection)
        ? new HashSet<E>((Collection<? extends E>) elements)
        : newHashSet(elements.iterator());
  }

  /**
   * Creates a <i>mutable</i> {@code HashSet} instance containing the given elements. A very thin

  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call
  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) {
    return (elements instanceof Collection)
        ? new HashSet<E>((Collection<? extends E>) elements)
        : newHashSet(elements.iterator());
  }

  /**
   * Creates a <i>mutable</i> {@code HashSet} instance containing the given elements. A very thin