Updated deprecated widgets with new one (#689)

experimental/federated_plugin/federated_plugin/example/lib/main.dart

@@ -34,9 +34,7 @@ class _HomePageState extends State<HomePage> {
       appBar: AppBar(
         title: Text('Federated Plugin Demo'),
       ),
-      body: Builder(
+      body: Center(
-        builder: (context) {
-          return Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: [
@@ -56,7 +54,7 @@ class _HomePageState extends State<HomePage> {
                     batteryLevel = result;
                   });
                 } catch (error) {
-                      Scaffold.of(context).showSnackBar(
+                  ScaffoldMessenger.of(context).showSnackBar(
                     SnackBar(
                       backgroundColor: Theme.of(context).primaryColor,
                       content: Text(error.message as String),
@@ -67,8 +65,6 @@ class _HomePageState extends State<HomePage> {
             ),
           ],
         ),
-          );
-        },
       ),
     );
   }

experimental/federated_plugin/federated_plugin/example/pubspec.lock

@@ -212,4 +212,4 @@ packages:
     version: "2.1.0-nullsafety.5"
 sdks:
   dart: ">=2.12.0-0.0 <3.0.0"
-  flutter: ">=1.20.0 <2.0.0"
+  flutter: ">=1.20.0"

experimental/federated_plugin/federated_plugin/pubspec.lock

@@ -198,4 +198,4 @@ packages:
     version: "2.1.0-nullsafety.5"
 sdks:
   dart: ">=2.12.0-0.0 <3.0.0"
-  flutter: ">=1.20.0 <2.0.0"
+  flutter: ">=1.20.0"