How to change OutlinedButton border color?

Flutter widget, I tried to change the OutlineButton border color by using BorderSide(color : Colors.blue). The OutlineButton always with grey color border no matter which color is set, but width change is applicable. How to change the OutlineButton border line color?

class OutlineButtonWidget extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return Center(
        child: OutlineButton(
            onPressed: null,
            borderSide: BorderSide(
                width: 5.0,
                color: Colors.blue,
                style: BorderStyle.solid,
            ),
            child: Text('outline button')
            ),
        ),
    );
  }
}

Use thestyle property:

OutlinedButton(
  onPressed: () {},
  child: Text('Outlined button'),
  style: OutlinedButton.styleFrom(
    side: BorderSide(width: 5.0, color: Colors.blue),
  ),
)