code: public TimeFrameFilterType getType() {
                  if (startDate == null && endDate == null) {
                          return TimeFrameFilterType.INOPERATIVE;
                  } else if (startDate != null && endDate == null) {
                          return TimeFrameFilterType.MIN_DATE;
                  } else if (startDate == null && endDate != null) {
                          return TimeFrameFilterType.MAX_DATE;
                  } else {
                          return TimeFrameFilterType.TIMEFRAME;
                  }
          }
docs: Returns the type of the time filter.
  
  @return