Recurring delisting through the terator

[Mystic]

Write a method that should be used through a course (using the collection terator) all elements of the list divided by a given sign in the form of a line. For example, there is a list containing the numbers between 1 and 5. When the method is called, the list should be displayed in a 1+2+3+4+5 format. Actually, the method works, but somehow I get a "1+2+3+4+5+" as a result. Where did I make a mistake that I got out after five more plus?

    public static String join(List values, String separator) {
        return join(values.iterator(), separator);
    }
public static String join(Iterator values, String separator) {

    if (!values.hasNext()) return "";

    String firstElement = values.next() + separator;    // Первый элемент списка
    String restElements = join(values, separator);
    return firstElement + restElements;
}

[meriah]

Replacement

String firstElement = values.next() + separator;

♪

String firstElement = values.next() + (values.hasNext() ? separator : "");