我试图为我的Flutter应用程序在ThemeData中应用自定义buttonStyle。一切正常，但BorderSide被忽略，并且始终是默认值（BorderSide.color = Colors.black和BorderSide.width = 1.0）
如何更改Theme中的BorderSide，使其变为红色，半径为2.0？

outlinedButtonTheme: OutlinedButtonThemeData(
  style: ButtonStyle(
    shape: MaterialStateProperty.resolveWith((states) {
      return RoundedRectangleBorder(
        // borderRadius is not ignored and gets applied to OutlinedButton => everything fine
        borderRadius: BorderRadius.zero,
        // here it gets interesting, the side-parameter is always ignored and defaults to `color: Colors.black` and `width: BorderSide.width = 1.0`
        side: BorderSide(color: Colors.red, width: 2.0),
      );
    }),
  ),
)

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