JPA Native Query with Kotlin and Spring

jpaNativeQuerySample.kt

@Service
class SalesOrderServiceImpl @Autowired constructor (
        val em: EntityManager
) : SalesOrderService {

  override fun getDailySalesData(reportFilter: ReportFilter)
      : List<SalesData> {
          val q = em.createNativeQuery("""
          SELECT
                  s.date,
                  sum(sd.price) as amount
          FROM sales s
          left join sales_details sd
            on s.id = sd.sales_id
              where
                  s.date between ?1 and ?2
          group by s.date
          """)
          .setParameter(1, reportFilter.getStartDateTimestamp())
          .setParameter(2, reportFilter.getEndDateTimestamp())

          val resultList = q.getResultList().toList()
          val result = resultList.map {
              it ->
                  val lst = it as Array<out Any>
                  SalesData(
                          lst[0] as? BigInteger,
                          lst[1] as? BigDecimal
                  )
          }
          return result
      }
}