borderRadius property
final
The border radius of both the indicator and the track.
If null, then the ProgressIndicatorThemeData.borderRadius will be used. If that is also null, then defaults to radius of 2, which produces a rounded shape with a rounded indicator. If ThemeData.useMaterial3 is false, then defaults to BorderRadius.zero, which produces a rectangular shape with a rectangular indicator.
Implementation
final BorderRadiusGeometry? borderRadius;