code: private String getNewDayOfWeekValue(String schedule, int dayOfWeekValue) {
      String newDayOfWeekValue = null;
  
      checkBadRequest(dayOfWeekValue >= 0 && dayOfWeekValue <= 7, "Schedule %s is invalid, day of week (%s) is not 0-7", schedule, dayOfWeekValue);
  
      switch (dayOfWeekValue) {
        case 7:
        case 0:
          newDayOfWeekValue = "SUN";
          break;
        case 1:
          newDayOfWeekValue = "MON";
          break;
        case 2:
          newDayOfWeekValue = "TUE";
          break;
        case 3:
          newDayOfWeekValue = "WED";
          break;
        case 4:
          newDayOfWeekValue = "THU";
          break;
        case 5:
          newDayOfWeekValue = "FRI";
          break;
        case 6:
          newDayOfWeekValue = "SAT";
          break;
        default:
          badRequest("Schedule %s is invalid, day of week (%s) is not 0-7", schedule, dayOfWeekValue);
          break;
      }
  
      return newDayOfWeekValue;
    }
docs: Standard cron: day of week (0 - 6) (0 to 6 are Sunday to Saturday, or use names; 7 is Sunday, the same as 0)
  Quartz: 1-7 or SUN-SAT