@Override
  public boolean equals(@Nullable Object other) {
    T theElement = this.theElement;
    if (theElement != null) {
      return other instanceof Set && ((Set<?>)other).size() == 1 && Objects.equals(((Set<?>)other).iterator().next(), theElement);
    }

    return super.equals(other);
  }
@Override
  public boolean equals(@Nullable Object other)