@Override
    public String toString() {
      StringBuilder builder = new StringBuilder();

      List<String> exdtParamList = new LinkedList<>();
      exdtParamList.add(EXDATE);
      if (value() != null) {
        exdtParamList.add(VALUE + "=" + value());
      }
      if (tzidparam() != null) {
        exdtParamList.add(TZID + "=" + tzidparam());
      }
      builder.append(String.join(";", exdtParamList) + ":" +
          String.join(",", exdtval()));
      return builder.toString();
    }
A method for parsing an ExDate string in an {@link ExDate}

@param exDateString a string containing ExDate information, excluding the EXDATE prefix
@return an {@link ExDate}
portability-types-common/src/main/java/org/datatransferproject/types/common/models/calendar/RecurrenceRule.java