*/

  @Override
  public boolean equals(@Nullable Object object) {
    if (object instanceof Set) {
      Set<?> that = (Set<?>) object;
      return (this.size() == that.size()) && this.containsAll(that);
    }
    return false;
  }

  @Override
  public int hashCode() {
    int hashCodeSum = 0;
    for (Object o : this) {
      hashCodeSum += (o == null) ? 0 : o.hashCode();

   */

  @Override
  public boolean equals(@Nullable Object object) {
    if (object instanceof Set) {
      Set<?> that = (Set<?>) object;
      return (this.size() == that.size()) && this.containsAll(that);
    }
    return false;
  }

  @Override
  public int hashCode() {
    int hashCodeSum = 0;
    for (Object o : this) {
      hashCodeSum += (o == null) ? 0 : o.hashCode();