color property
Color of the axis line. Color will be applied based on the brightness property of the app.
Defaults to null.
Widget build(BuildContext context) {
    return Container(
        child: SfCartesianChart(
            primaryXAxis: NumericAxis(
                 axisLine:AxisLine(
                   color:Colors.blue,
                 )
                ),
        ));
}
Implementation
final Color? color;