docs: private int getNextDayOfWeek(int day, int dayOfWeek)
      {
          if (!contains(daysOfWeek, dayOfWeek))
          {
              long higher = higher(daysOfWeek, dayOfWeek);
              if (higher != 0)
              {
                  return day + (first(higher) - dayOfWeek);
              }
  
              return day + (7 - dayOfWeek) + first(daysOfWeek);
          }
  
          return day;
      }