code: public static CopticCalendar of(
          int cyear,
          int cmonth,
          int cdom
      ) {
  
          if (!CALSYS.isValid(CopticEra.ANNO_MARTYRUM, cyear, cmonth, cdom)) {
              throw new IllegalArgumentException(
                  "Invalid Coptic date: year=" + cyear + ", month=" + cmonth + ", day=" + cdom);
          }
  
          return new CopticCalendar(cyear, cmonth, cdom);
  
      }
docs: /*[deutsch]
  <p>Erzeugt ein neues koptisches Kalenderdatum. </p>
  
  @param   cyear   Coptic year in the range 1-9999
  @param   cmonth  Coptic month in range 1-13
  @param   cdom    Coptic day of month in range 1-30
  @return  new instance of {@code CopticCalendar}
  @throws  IllegalArgumentException in case of any inconsistencies
  @since   3.11/4.8