//workaround! Select correct Type public async Task <HeartRateData> GetHeartRateData(DateTime startDate, DateTime endDate, bool withTime = false, Action <HeartRateData> action = null) { //dates have to be same day for Time! if (withTime && endDate.Date == startDate.Date) { return(await base.GetData <HeartRateIntradayTimeSeriesTime>(APIEndpoints.HeartRatePath(startDate, endDate, withTime), action)); } else { return(await base.GetData <HeartRateIntradayTimeSeries>(APIEndpoints.HeartRatePath(startDate, endDate, withTime), action)); } }