cdm/src/main/java/ucar/nc2/time/CalendarDateUnit.java
static public CalendarDateUnit of(String calendarName, String udunitString) {
    Calendar calt = Calendar.get(calendarName);
    if (calt == null) calt = Calendar.getDefault();
    return new CalendarDateUnit(calt, udunitString);
  }
static public CalendarDateUnit of(String calendarName, String udunitString) {
    Calendar calt = Calendar.get(calendarName);
    if (calt == null) calt = Calendar.getDefault();
    return new CalendarDateUnit(calt, udunitString);
  }
Create a CalendarDateUnit from a calendar name and a udunit string = "unit since calendarDate"
@param calendarName must match a calendar enum, or one of its aliases, see ucar.nc2.time.Calendar.get()
@param udunitString "unit since calendarDate"
@return CalendarDateUnit
@throws IllegalArgumentException if udunitString is not paresable