public TimePeriod getValueFromLuceneField(String documentValue) {
   Date date = LuceneUtils.stringToDate(documentValue);
   if (date == null) {
     return null;
   }
   return RegularTimePeriod.createInstance(timePeriodClass, date, periodTimeZone);
 }
 public String getIndexedValue(final Date date) {
   return LuceneUtils.dateToString(date);
 }