code: private Calendar getValidUntil() {
  
          // Get valid until date
          Date validUntil = getModel().getValidUntil();
          if (validUntil == null)
              return null;
  
          // Convert to end-of-day within defined time zone
          Calendar validUntilCalendar = Calendar.getInstance(getTimeZone());
          validUntilCalendar.setTime(validUntil);
          validUntilCalendar.set(Calendar.HOUR_OF_DAY,  23);
          validUntilCalendar.set(Calendar.MINUTE,       59);
          validUntilCalendar.set(Calendar.SECOND,       59);
          validUntilCalendar.set(Calendar.MILLISECOND, 999);
          return validUntilCalendar;
  
      }
docs: Returns the date after which this account becomes invalid. The time
  components of the resulting Calendar object will be set to the last
  millisecond of the day in question (23:59:59.999).
  
  @return
  The date after which this account becomes invalid.