cdm/src/main/java/ucar/nc2/time/CalendarDate.java
@Nullable
  public static CalendarDate parseUdunitsOrIso(String calendarName, String isoOrUdunits) {
    CalendarDate result;
    try {
      result = parseISOformat(calendarName, isoOrUdunits);
    } catch (Exception e) {
      try {
        result = parseUdunits(calendarName, isoOrUdunits);
      } catch (Exception e2) {
        return  null;
      }
    }
    return result;
  }
@Nullable
  public static CalendarDate parseUdunitsOrIso(String calendarName, String isoOrUdunits) {
    CalendarDate result;
    try {
      result = parseISOformat(calendarName, isoOrUdunits);
    } catch (Exception e) {
      try {
        result = parseUdunits(calendarName, isoOrUdunits);
      } catch (Exception e2) {
        return  null;
      }
    }
    return result;
  }
Get CalendarDate from ISO date string
@param calendarName get Calendar from Calendar.get(calendarName). may be null
@param isoOrUdunits ISO or udunits date string
@return  CalendarDate or null if not valid