code: @Override
      public int getFirstDayOfWeek(Locale country) {
  
          String fw = country.getUnicodeLocaleType("fw");
  
          if (fw != null) {
              Weekday wd = toEnum(fw);
              if (wd != null) { // else ignore fw-extension
                  return wd.getValue();
              }
          }
  
          if (this.firstDayOfWeek.isEmpty()) {
              // fallback
              GregorianCalendar gc = new GregorianCalendar(country);
              int fd = gc.getFirstDayOfWeek();
              return ((fd == 1) ? 7 : (fd - 1));
          }
  
          String key = FormatUtils.getRegion(country);
          Weekday first = Weekday.MONDAY;
  
          if (this.firstDayOfWeek.containsKey(key)) {
              first = this.firstDayOfWeek.get(key);
          }
  
          return first.getValue();
  
      }
docs: ~ Methoden ----------------------------------------------------------