BottomNavigationBarItem colore sciolto quando ci sono quattro

BottomNavigationBarItem colore sciolto quando ci sono quattro

bottomNavigationBar: new BottomNavigationBar(
    type: BottomNavigationBarType.fixed,
    items: [
    new BottomNavigationBarItem(icon: new Icon(Icons.add), title: new Text("Text")),
    new BottomNavigationBarItem(icon: new Icon(Icons.person), title: new Text("Contact")),
    new BottomNavigationBarItem(icon: new Icon(Icons.accessibility), title: new Text("Acess")),
    new BottomNavigationBarItem(icon: new Icon(Icons.account_balance), title: new Text("Balance"))
  ]),