sortingOrder property Null safety

SortingOrder? sortingOrder

The data points in the series can be sorted in ascending or descending order. The data points will be rendered in the specified order if it is set to none.

Default to none

Also refer SortingOrder

Widget build(BuildContext context) {
   return Container(
       child: SfCartesianChart(
           series: <BarSeries<SalesData, num>>[
               BarSeries<SalesData, num>(
                   sortingOrder: SortingOrder.ascending,


final SortingOrder? sortingOrder;