code: public static CalendarPeriod<CalendarMonth> between(
          CalendarMonth m1,
          CalendarMonth m2
      ) {
  
          return new FixedCalendarPeriod<>(m1, m2, FixedCalendarTimeLine.forMonths());
  
      }
docs: /*[deutsch]
  Erzeugt eine {@code CalendarPeriod} f&uuml;r die angegebene Monatsspanne.
  
  @param   m1  first calendar month
  @param   m2  last calendar month (inclusive)
  @return  CalendarPeriod