side property
final
The side for the circular border of the radio button, in all WidgetStates.
This property can be a BorderSide or a WidgetStateBorderSide to leverage widget state resolution.
Resolves in the following states:
If null, then RadioThemeData.side of ThemeData.radioTheme is used. If that is also null, the default value is a border using the fill color.
Implementation
final BorderSide? side;