i want to have a top radius on my bottomnavabar in flutter

Question

class StartApp extends StatelessWidget {
  const StartApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Provider.of<BottomNavBarController>(context)
          .widgetOptions
          .elementAt(
              Provider.of<BottomNavBarController>(context).selectedIndex),
      bottomNavigationBar: Container(
        decoration: footercontainerDecoration,
        child: BottomNavigationBar(
          backgroundColor: Colors.white,
          currentIndex:
              Provider.of<BottomNavBarController>(context).selectedIndex,
          onTap: Provider.of<BottomNavBarController>(context).onItemTapped,
          type: BottomNavigationBarType.fixed,
          selectedItemColor: Colors.black,
          selectedLabelStyle: const TextStyle(color: Colors.black),
          unselectedItemColor: Colors.grey,
          unselectedLabelStyle: const TextStyle(color: Colors.grey),
          items: const [
            BottomNavigationBarItem(
              icon: ImageIcon(
                AssetImage("assets/flavicons/home.png"),
              ),
              label: "Home",
            ),
            BottomNavigationBarItem(
                icon: ImageIcon(
                  AssetImage("assets/flavicons/charts.png"),
                ),
                label: "Home"),
            BottomNavigationBarItem(
                icon: ImageIcon(
                  AssetImage("assets/flavicons/ticket.png"),
                ),
                label: "Home"),
            BottomNavigationBarItem(
                icon: ImageIcon(
                  AssetImage("assets/flavicons/atm.png"),
                ),
                label: "Home"),
          ],
        ),
      ),
    );
  }
}