anchor.diff:    final FloatingActionButton floatingActionButton;
     final NavigationTypeResolver navigationTypeResolver;
   
  -  AdaptiveNavigationScaffold({
  +  const AdaptiveNavigationScaffold({
  +    Key key,
       this.title,
       this.body,
       @required this.currentIndex,
  
positive.code:   @override
    Widget build(BuildContext context) {
      final NavigationTypeResolver navigationTypeResolver =
          widget.navigationTypeResolver ?? _defaultNavigationTypeResolver;
      switch (navigationTypeResolver(context)) {
        case NavigationType.bottomNavigation:
          // Show a Scaffold with a BottomNavigationBar.
          return Scaffold(
            body: widget.body,
            appBar: AppBar(title: widget.title),
            bottomNavigationBar: BottomNavigationBar(
              items: [
                for (final destination in widget.destinations)
                  BottomNavigationBarItem(
                    icon: Icon(destination.icon),
                    title: Text(destination.title),
                  ),
              ],
              currentIndex: widget.currentIndex,
              onTap: widget.onNavigationIndexChange,
            ),
            floatingActionButton: widget.floatingActionButton,
          );
        case NavigationType.navigationRail:
          // Show a Scaffold with a body containing a NavigationRail.
          return Scaffold(
            appBar: AppBar(
              title: widget.title,
            ),
            body: Row(
              children: [
                NavigationRail(
                  leading: widget.floatingActionButton,
                  destinations: [
                    for (final destination in widget.destinations)
                      NavigationRailDestination(
                        icon: Icon(destination.icon),
                        label: Text(destination.title),
                      ),
                  ],
                  selectedIndex: widget.currentIndex,
                  onDestinationSelected: widget.onNavigationIndexChange ?? (_) {},
                ),
                VerticalDivider(
                  width: 1,
                  thickness: 1,
                ),
                Expanded(
                  child: widget.body,
                ),
              ],
            ),
  
negative.code: /// A widget that adapts to the current display size, displaying a [Drawer],
  /// [NavigationRail], or [BottomNavigationBar]. Navigation destinations are
  /// defined in the [destinations] parameter.
  class AdaptiveNavigationScaffold extends StatelessWidget {
    final Widget title;
    final Widget body;
    final int currentIndex;
  