code: public Weekday getDayOfWeek() {
  
          Weekday dow = this.weekday;
  
          if (dow == null) {
              dow = Weekday.valueOf(GregorianMath.getDayOfWeek(this.year, this.month, this.dayOfMonth));
          }
  
          return dow;
  
      }
docs: /*[deutsch]
  <p>Ermittelt den Wochentag. </p>
  
  @return  Weekday
  @since   3.13/4.10