enable use_key_in_widget_constructors lint (#77032)

analysis_options.yaml

@@ -168,8 +168,8 @@ linter:
     - prefer_if_null_operators
     - prefer_initializing_formals
     - prefer_inlined_adds
-    # - prefer_int_literals # not yet tested
-    # - prefer_interpolation_to_compose_strings # not yet tested
+    # - prefer_int_literals # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#use-double-literals-for-double-constants
+    # - prefer_interpolation_to_compose_strings # doesn't work with raw strings, see https://github.com/dart-lang/linter/issues/2490
     - prefer_is_empty
     - prefer_is_not_empty
     - prefer_is_not_operator
@@ -220,7 +220,7 @@ linter:
     # - use_function_type_syntax_for_parameters # not yet tested
     # - use_if_null_to_convert_nulls_to_bools # not yet tested
     - use_is_even_rather_than_modulo
-    # - use_key_in_widget_constructors # not yet tested
+    - use_key_in_widget_constructors
     - use_late_for_private_fields_and_variables
     # - use_named_constants # not yet yested
     - use_raw_strings

dev/benchmarks/complex_layout/lib/main.dart

@@ -7,13 +7,15 @@ import 'package:flutter/scheduler.dart' show timeDilation;
 
 void main() {
   runApp(
-    ComplexLayoutApp()
+    const ComplexLayoutApp()
   );
 }
 
 enum ScrollMode { complex, tile }
 
 class ComplexLayoutApp extends StatefulWidget {
+  const ComplexLayoutApp({Key key}) : super(key: key);
+
   @override
   ComplexLayoutAppState createState() => ComplexLayoutAppState();
 
@@ -68,7 +70,7 @@ class TileScrollLayout extends StatelessWidget {
             child: Material(
               elevation: (index % 5 + 1).toDouble(),
               color: Colors.white,
-              child: IconBar(),
+              child: const IconBar(),
             ),
           );
         },
@@ -101,7 +103,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
               print('Pressed search');
             },
           ),
-          TopBarMenu(),
+          const TopBarMenu(),
         ],
       ),
       body: Column(
@@ -118,7 +120,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
               },
             ),
           ),
-          BottomBar(),
+          const BottomBar(),
         ],
       ),
       drawer: const GalleryDrawer(),
@@ -127,6 +129,8 @@ class ComplexLayoutState extends State<ComplexLayout> {
 }
 
 class TopBarMenu extends StatelessWidget {
+  const TopBarMenu({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return PopupMenuButton<String>(
@@ -178,7 +182,7 @@ class TopBarMenu extends StatelessWidget {
 }
 
 class MenuItemWithIcon extends StatelessWidget {
-  const MenuItemWithIcon(this.icon, this.title, this.subtitle);
+  const MenuItemWithIcon(this.icon, this.title, this.subtitle, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -209,15 +213,15 @@ class FancyImageItem extends StatelessWidget {
     return ListBody(
       children: <Widget>[
         UserHeader('Ali Connors $index'),
-        ItemDescription(),
-        ItemImageBox(),
-        InfoBar(),
+        const ItemDescription(),
+        const ItemImageBox(),
+        const InfoBar(),
         const Padding(
           padding: EdgeInsets.symmetric(horizontal: 8.0),
           child: Divider(),
         ),
-        IconBar(),
-        FatDivider(),
+        const IconBar(),
+        const FatDivider(),
       ],
     );
   }
@@ -233,19 +237,21 @@ class FancyGalleryItem extends StatelessWidget {
       children: <Widget>[
         const UserHeader('Ali Connors'),
         ItemGalleryBox(index),
-        InfoBar(),
+        const InfoBar(),
         const Padding(
           padding: EdgeInsets.symmetric(horizontal: 8.0),
           child: Divider(),
         ),
-        IconBar(),
-        FatDivider(),
+        const IconBar(),
+        const FatDivider(),
       ],
     );
   }
 }
 
 class InfoBar extends StatelessWidget {
+  const InfoBar({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -262,6 +268,8 @@ class InfoBar extends StatelessWidget {
 }
 
 class IconBar extends StatelessWidget {
+  const IconBar({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -279,7 +287,7 @@ class IconBar extends StatelessWidget {
 }
 
 class IconWithText extends StatelessWidget {
-  const IconWithText(this.icon, this.title);
+  const IconWithText(this.icon, this.title, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -300,7 +308,7 @@ class IconWithText extends StatelessWidget {
 }
 
 class MiniIconWithText extends StatelessWidget {
-  const MiniIconWithText(this.icon, this.title);
+  const MiniIconWithText(this.icon, this.title, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -329,6 +337,8 @@ class MiniIconWithText extends StatelessWidget {
 }
 
 class FatDivider extends StatelessWidget {
+  const FatDivider({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -339,7 +349,7 @@ class FatDivider extends StatelessWidget {
 }
 
 class UserHeader extends StatelessWidget {
-  const UserHeader(this.userName);
+  const UserHeader(this.userName, {Key key}) : super(key: key);
 
   final String userName;
 
@@ -380,7 +390,7 @@ class UserHeader extends StatelessWidget {
               ],
             ),
           ),
-          TopBarMenu(),
+          const TopBarMenu(),
         ],
       ),
     );
@@ -388,6 +398,8 @@ class UserHeader extends StatelessWidget {
 }
 
 class ItemDescription extends StatelessWidget {
+  const ItemDescription({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const Padding(
@@ -398,6 +410,8 @@ class ItemDescription extends StatelessWidget {
 }
 
 class ItemImageBox extends StatelessWidget {
+  const ItemImageBox({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -477,7 +491,7 @@ class ItemImageBox extends StatelessWidget {
 }
 
 class ItemGalleryBox extends StatelessWidget {
-  const ItemGalleryBox(this.index);
+  const ItemGalleryBox(this.index, {Key key}) : super(key: key);
 
   final int index;
 
@@ -548,6 +562,8 @@ class ItemGalleryBox extends StatelessWidget {
 }
 
 class BottomBar extends StatelessWidget {
+  const BottomBar({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -574,7 +590,7 @@ class BottomBar extends StatelessWidget {
 }
 
 class BottomBarButton extends StatelessWidget {
-  const BottomBarButton(this.icon, this.title);
+  const BottomBarButton(this.icon, this.title, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -618,7 +634,7 @@ class GalleryDrawer extends StatelessWidget {
         key: const PageStorageKey<String>('gallery-drawer'),
         padding: EdgeInsets.zero,
         children: <Widget>[
-          FancyDrawerHeader(),
+          const FancyDrawerHeader(),
           ListTile(
             key: const Key('scroll-switcher'),
             title: const Text('Scroll Mode'),
@@ -668,6 +684,8 @@ class GalleryDrawer extends StatelessWidget {
 }
 
 class FancyDrawerHeader extends StatelessWidget {
+  const FancyDrawerHeader({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(

dev/benchmarks/complex_layout/test_memory/scroll_perf.dart

@@ -27,7 +27,7 @@ Future<void> main() async {
       ready.complete();
     },
     behavior: HitTestBehavior.opaque,
-    child: IgnorePointer(
+    child: const IgnorePointer(
       ignoring: true,
       child: ComplexLayoutApp(),
     ),
@@ -45,7 +45,7 @@ Future<void> main() async {
 
   // remove onTap handler, enable pointer events for app
   runApp(GestureDetector(
-    child: IgnorePointer(
+    child: const IgnorePointer(
       ignoring: false,
       child: ComplexLayoutApp(),
     ),

dev/benchmarks/macrobenchmarks/lib/main.dart

@@ -29,7 +29,7 @@ const String kMacrobenchmarks = 'Macrobenchmarks';
 void main() => runApp(const MacrobenchmarksApp());
 
 class MacrobenchmarksApp extends StatelessWidget {
-  const MacrobenchmarksApp({this.initialRoute = '/'});
+  const MacrobenchmarksApp({Key key, this.initialRoute = '/'}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -37,25 +37,25 @@ class MacrobenchmarksApp extends StatelessWidget {
       title: kMacrobenchmarks,
       initialRoute: initialRoute,
       routes: <String, WidgetBuilder>{
-        '/': (BuildContext context) => HomePage(),
-        kCullOpacityRouteName: (BuildContext context) => CullOpacityPage(),
-        kCubicBezierRouteName: (BuildContext context) => CubicBezierPage(),
-        kBackdropFilterRouteName: (BuildContext context) => BackdropFilterPage(),
-        kPostBackdropFilterRouteName: (BuildContext context) => PostBackdropFilterPage(),
-        kSimpleAnimationRouteName: (BuildContext context) => SimpleAnimationPage(),
-        kPictureCacheRouteName: (BuildContext context) => PictureCachePage(),
-        kLargeImageChangerRouteName: (BuildContext context) => LargeImageChangerPage(),
-        kLargeImagesRouteName: (BuildContext context) => LargeImagesPage(),
-        kTextRouteName: (BuildContext context) => TextPage(),
-        kFullscreenTextRouteName: (BuildContext context) => TextFieldPage(),
-        kAnimatedPlaceholderRouteName: (BuildContext context) => AnimatedPlaceholderPage(),
-        kColorFilterAndFadeRouteName: (BuildContext context) => ColorFilterAndFadePage(),
+        '/': (BuildContext context) => const HomePage(),
+        kCullOpacityRouteName: (BuildContext context) => const CullOpacityPage(),
+        kCubicBezierRouteName: (BuildContext context) => const CubicBezierPage(),
+        kBackdropFilterRouteName: (BuildContext context) => const BackdropFilterPage(),
+        kPostBackdropFilterRouteName: (BuildContext context) => const PostBackdropFilterPage(),
+        kSimpleAnimationRouteName: (BuildContext context) => const SimpleAnimationPage(),
+        kPictureCacheRouteName: (BuildContext context) => const PictureCachePage(),
+        kLargeImageChangerRouteName: (BuildContext context) => const LargeImageChangerPage(),
+        kLargeImagesRouteName: (BuildContext context) => const LargeImagesPage(),
+        kTextRouteName: (BuildContext context) => const TextPage(),
+        kFullscreenTextRouteName: (BuildContext context) => const TextFieldPage(),
+        kAnimatedPlaceholderRouteName: (BuildContext context) => const AnimatedPlaceholderPage(),
+        kColorFilterAndFadeRouteName: (BuildContext context) => const ColorFilterAndFadePage(),
         kFadingChildAnimationRouteName: (BuildContext context) => const FilteredChildAnimationPage(FilterType.opacity),
         kImageFilteredTransformAnimationRouteName: (BuildContext context) => const FilteredChildAnimationPage(FilterType.rotateFilter),
         kMultiWidgetConstructionRouteName: (BuildContext context) => const MultiWidgetConstructTable(10, 20),
-        kHeavyGridViewRouteName: (BuildContext context) => HeavyGridViewPage(),
-        kSimpleScrollRouteName: (BuildContext context) => SimpleScroll(),
-        kStackSizeRouteName: (BuildContext context) => StackSizePage(),
+        kHeavyGridViewRouteName: (BuildContext context) => const HeavyGridViewPage(),
+        kSimpleScrollRouteName: (BuildContext context) => const SimpleScroll(),
+        kStackSizeRouteName: (BuildContext context) => const StackSizePage(),
       },
     );
   }
@@ -64,6 +64,8 @@ class MacrobenchmarksApp extends StatelessWidget {
 }
 
 class HomePage extends StatelessWidget {
+  const HomePage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/benchmarks/macrobenchmarks/lib/src/animated_placeholder.dart

@@ -24,6 +24,8 @@ const String kBlueSquare = 'iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAYAAAAeP4ixAAAASEl'
 /// A 10x10 grid of animated looping placeholder gifts that fade into a
 /// blue square.
 class AnimatedPlaceholderPage extends StatelessWidget {
+  const AnimatedPlaceholderPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return GridView.builder(

dev/benchmarks/macrobenchmarks/lib/src/backdrop_filter.dart

@@ -7,6 +7,8 @@ import 'dart:ui';
 import 'package:flutter/material.dart';
 
 class BackdropFilterPage extends StatefulWidget {
+  const BackdropFilterPage({Key key}) : super(key: key);
+
   @override
   _BackdropFilterPageState createState() => _BackdropFilterPageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/color_filter_and_fade.dart

@@ -9,6 +9,8 @@ import 'package:flutter/material.dart';
 // This tests whether the Opacity layer raster cache works with color filters.
 // See https://github.com/flutter/flutter/issues/51975.
 class ColorFilterAndFadePage extends StatefulWidget {
+  const ColorFilterAndFadePage({Key key}) : super(key: key);
+
   @override
   _ColorFilterAndFadePageState createState() => _ColorFilterAndFadePageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/cubic_bezier.dart

@@ -8,6 +8,8 @@ import 'package:flutter/material.dart';
 
 // Based on https://github.com/eseidelGoogle/bezier_perf/blob/master/lib/main.dart
 class CubicBezierPage extends StatelessWidget {
+  const CubicBezierPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Center(
@@ -22,7 +24,7 @@ class CubicBezierPage extends StatelessWidget {
 }
 
 class Bezier extends StatelessWidget {
-  const Bezier(this.color, this.scale, {this.blur = 0.0, this.delay = 0.0});
+  const Bezier(this.color, this.scale, {Key key, this.blur = 0.0, this.delay = 0.0}) : super(key: key);
 
   final Color color;
   final double scale;
@@ -91,7 +93,7 @@ class PathDetail {
 }
 
 class AnimatedBezier extends StatefulWidget {
-  const AnimatedBezier(this.color, this.scale, {this.blur = 0.0, this.delay});
+  const AnimatedBezier(this.color, this.scale, {Key key, this.blur = 0.0, this.delay}) : super(key: key);
 
   final Color color;
   final double scale;

dev/benchmarks/macrobenchmarks/lib/src/cull_opacity.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class CullOpacityPage extends StatefulWidget {
+  const CullOpacityPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _CullOpacityPageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/filtered_child_animation.dart

@@ -12,10 +12,11 @@ enum FilterType {
 }
 
 class FilteredChildAnimationPage extends StatefulWidget {
-  const FilteredChildAnimationPage(this.initialFilterType, [
+  const FilteredChildAnimationPage(this.initialFilterType, {
+    Key key,
     this.initialComplexChild = true,
     this.initialUseRepaintBoundary = true,
-  ]);
+  }) : super(key: key);
 
   final FilterType initialFilterType;
   final bool initialComplexChild;

dev/benchmarks/macrobenchmarks/lib/src/fullscreenTextField.dart

@@ -48,6 +48,8 @@ const String textLotsOfText = 'Lorem ipsum dolor sit amet, consectetur '
   '🦻 👃 🫀 🫁 🧠 🦷 🦴 👀 👁 👅 👄 💋 🩸';
 
 class TextFieldPage extends StatelessWidget {
+  const TextFieldPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(

dev/benchmarks/macrobenchmarks/lib/src/heavy_grid_view.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class HeavyGridViewPage extends StatelessWidget {
+  const HeavyGridViewPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return GridView.builder(

dev/benchmarks/macrobenchmarks/lib/src/large_image_changer.dart

@@ -8,6 +8,8 @@ import 'package:flutter/material.dart';
 
 /// Displays a new (from image cache's perspective) large image every 500ms.
 class LargeImageChangerPage extends StatefulWidget {
+  const LargeImageChangerPage({Key key}) : super(key: key);
+
   @override
   _LargeImageChangerState createState() => _LargeImageChangerState();
 }

dev/benchmarks/macrobenchmarks/lib/src/large_images.dart

@@ -7,6 +7,8 @@ import 'dart:typed_data';
 import 'package:flutter/material.dart';
 
 class LargeImagesPage extends StatelessWidget {
+  const LargeImagesPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final ImageCache imageCache = PaintingBinding.instance.imageCache;

dev/benchmarks/macrobenchmarks/lib/src/picture_cache.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class PictureCachePage extends StatelessWidget {
+  const PictureCachePage({Key key}) : super(key: key);
+
   static const List<String> kTabNames = <String>['1', '2', '3', '4', '5'];
 
   @override

dev/benchmarks/macrobenchmarks/lib/src/post_backdrop_filter.dart

@@ -7,6 +7,8 @@ import 'dart:ui';
 import 'package:flutter/material.dart';
 
 class PostBackdropFilterPage extends StatefulWidget {
+  const PostBackdropFilterPage({Key key}) : super(key: key);
+
   @override
   _PostBackdropFilterPageState createState() => _PostBackdropFilterPageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/simple_animation.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class SimpleAnimationPage extends StatelessWidget {
+  const SimpleAnimationPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const Center(child: LinearProgressIndicator());

dev/benchmarks/macrobenchmarks/lib/src/simple_scroll.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class SimpleScroll extends StatelessWidget {
+  const SimpleScroll({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return ListView(

dev/benchmarks/macrobenchmarks/lib/src/stack_size.dart

@@ -81,6 +81,8 @@ final GetStackPointerCallback getStackPointer = () {
 }();
 
 class StackSizePage extends StatelessWidget {
+  const StackSizePage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(
@@ -89,7 +91,7 @@ class StackSizePage extends StatelessWidget {
           Container(
             width: 200,
             height: 100,
-            child: ParentWidget(),
+            child: const ParentWidget(),
           ),
         ],
       ),
@@ -98,6 +100,8 @@ class StackSizePage extends StatelessWidget {
 }
 
 class ParentWidget extends StatelessWidget {
+  const ParentWidget({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final int myStackSize = getStackPointer();

dev/benchmarks/macrobenchmarks/lib/src/text.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class TextPage extends StatelessWidget {
+  const TextPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(

dev/benchmarks/macrobenchmarks/lib/src/web/bench_text_layout.dart

@@ -271,7 +271,7 @@ class BenchBuildColorsGrid extends WidgetBuildRecorder {
   @override
   Widget createWidget() {
     _counter++;
-    return MaterialApp(home: ColorsDemo());
+    return const MaterialApp(home: ColorsDemo());
   }
 }
 
@@ -469,6 +469,8 @@ class PaletteTabView extends StatelessWidget {
 }
 
 class ColorsDemo extends StatelessWidget {
+  const ColorsDemo({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return DefaultTabController(

dev/benchmarks/macrobenchmarks/lib/src/web/bench_wrapbox_scroll.dart

@@ -84,7 +84,7 @@ class _MyHomePageState extends State<MyHomePage> {
 }
 
 class ProductPreview extends StatelessWidget {
-  const ProductPreview(this.previewIndex);
+  const ProductPreview(this.previewIndex, {Key key}) : super(key: key);
 
   final int previewIndex;
 

dev/benchmarks/macrobenchmarks/test/frame_policy.dart

@@ -17,7 +17,7 @@ void main() {
   testWidgets(
     'Frame Counter and Input Delay for benchmarkLive',
     (WidgetTester tester) async {
-      await tester.pumpWidget(MaterialApp(home: Scaffold(body: SimpleScroll())));
+      await tester.pumpWidget(const MaterialApp(home: Scaffold(body: SimpleScroll())));
       await tester.pumpAndSettle();
       final Offset location = tester.getCenter(find.byType(ListView));
       int frameCount = 0;

dev/benchmarks/microbenchmarks/lib/gestures/apps/button_matrix_app.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class ButtonMatrixApp extends StatefulWidget {
+  const ButtonMatrixApp({Key key}) : super(key: key);
+
   @override
   ButtonMatrixAppState createState() => ButtonMatrixAppState();
 }
@@ -48,5 +50,5 @@ class ButtonMatrixAppState extends State<ButtonMatrixApp> {
 }
 
 void main() {
-  runApp(ButtonMatrixApp());
+  runApp(const ButtonMatrixApp());
 }

dev/benchmarks/multiple_flutters/module/lib/main.dart

@@ -13,7 +13,7 @@ void topMain() => runApp(const MyApp(Colors.green));
 void bottomMain() => runApp(const MyApp(Colors.purple));
 
 class MyApp extends StatelessWidget {
-  const MyApp(this.color);
+  const MyApp(this.color, {Key key}) : super(key: key);
 
   final Color color;
 

dev/benchmarks/test_apps/stocks/lib/main.dart

@@ -20,6 +20,8 @@ import 'stock_symbol_viewer.dart';
 import 'stock_types.dart';
 
 class StocksApp extends StatefulWidget {
+  const StocksApp({Key key}) : super(key: key);
+
   @override
   StocksAppState createState() => StocksAppState();
 }
@@ -109,5 +111,5 @@ class StocksAppState extends State<StocksApp> {
 }
 
 void main() {
-  runApp(StocksApp());
+  runApp(const StocksApp());
 }

dev/benchmarks/test_apps/stocks/lib/stock_home.dart

@@ -52,7 +52,7 @@ class _NotImplementedDialog extends StatelessWidget {
 }
 
 class StockHome extends StatefulWidget {
-  const StockHome(this.stocks, this.configuration, this.updater);
+  const StockHome(this.stocks, this.configuration, this.updater, {Key key}) : super(key: key);
 
   final StockData stocks;
   final StockConfiguration configuration;

dev/benchmarks/test_apps/stocks/lib/stock_settings.dart

@@ -7,7 +7,7 @@ import 'package:flutter/material.dart';
 import 'stock_types.dart';
 
 class StockSettings extends StatefulWidget {
-  const StockSettings(this.configuration, this.updater);
+  const StockSettings(this.configuration, this.updater, {Key key}) : super(key: key);
 
   final StockConfiguration configuration;
   final ValueChanged<StockConfiguration> updater;

dev/benchmarks/test_apps/stocks/lib/stock_symbol_viewer.dart

@@ -65,7 +65,7 @@ class _StockSymbolView extends StatelessWidget {
 }
 
 class StockSymbolPage extends StatelessWidget {
-  const StockSymbolPage({ this.symbol, this.stocks });
+  const StockSymbolPage({ Key key, this.symbol, this.stocks }) : super(key: key);
 
   final String symbol;
   final StockData stocks;
@@ -113,7 +113,7 @@ class StockSymbolPage extends StatelessWidget {
 }
 
 class StockSymbolBottomSheet extends StatelessWidget {
-  const StockSymbolBottomSheet({ this.stock });
+  const StockSymbolBottomSheet({ Key key, this.stock }) : super(key: key);
 
   final Stock stock;
 

dev/integration_tests/abstract_method_smoke_test/lib/main.dart

@@ -9,11 +9,13 @@ Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
   const MethodChannel channel = MethodChannel('com.example.abstract_method_smoke_test');
   await channel.invokeMethod<void>('show_keyboard');
-  runApp(MyApp());
+  runApp(const MyApp());
   print('Test suceeded');
 }
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -21,12 +23,14 @@ class MyApp extends StatelessWidget {
       theme: ThemeData(
         primarySwatch: Colors.blue,
       ),
-      home: HomePage(),
+      home: const HomePage(),
     );
   }
 }
 
 class HomePage extends StatefulWidget {
+  const HomePage({Key key}) : super(key: key);
+
   @override
   _HomePage createState() => _HomePage();
 }
@@ -40,7 +44,7 @@ class _HomePage extends State<HomePage> {
     // https://github.com/flutter/flutter/issues/40126
     WidgetsBinding.instance.addPostFrameCallback((_) async {
       Navigator.of(context).push(
-          MaterialPageRoute<void>(builder: (_) => SecondPage()));
+          MaterialPageRoute<void>(builder: (_) => const SecondPage()));
     });
   }
 
@@ -51,6 +55,8 @@ class _HomePage extends State<HomePage> {
 }
 
 class SecondPage extends StatelessWidget {
+  const SecondPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/integration_tests/android_semantics_testing/lib/main.dart

@@ -43,14 +43,14 @@ Future<String> dataHandler(String message) async {
 }
 
 Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
-  selectionControlsRoute : (BuildContext context) => SelectionControlsPage(),
-  popupControlsRoute : (BuildContext context) => PopupControlsPage(),
-  textFieldRoute : (BuildContext context) => TextFieldPage(),
-  headingsRoute: (BuildContext context) => HeadingsPage(),
+  selectionControlsRoute : (BuildContext context) => const SelectionControlsPage(),
+  popupControlsRoute : (BuildContext context) => const PopupControlsPage(),
+  textFieldRoute : (BuildContext context) => const TextFieldPage(),
+  headingsRoute: (BuildContext context) => const HeadingsPage(),
 };
 
 class TestApp extends StatelessWidget {
-  const TestApp();
+  const TestApp({Key key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {

dev/integration_tests/android_semantics_testing/lib/src/tests/controls_page.dart

@@ -9,6 +9,8 @@ export 'controls_constants.dart';
 
 /// A test page with a checkbox, three radio buttons, and a switch.
 class SelectionControlsPage extends StatefulWidget {
+  const SelectionControlsPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _SelectionControlsPageState();
 }

dev/integration_tests/android_semantics_testing/lib/src/tests/headings_page.dart

@@ -9,6 +9,8 @@ export 'headings_constants.dart';
 
 /// A test page with an app bar and some body text for testing heading flags.
 class HeadingsPage extends StatelessWidget {
+  const HeadingsPage({Key key}) : super(key: key);
+
   static const ValueKey<String> _appBarTitleKey = ValueKey<String>(appBarTitleKeyValue);
   static const ValueKey<String> _bodyTextKey = ValueKey<String>(bodyTextKeyValue);
 

dev/integration_tests/android_semantics_testing/lib/src/tests/popup_page.dart

@@ -10,6 +10,8 @@ export 'popup_constants.dart';
 
 /// A page with a popup menu, a dropdown menu, and a modal alert.
 class PopupControlsPage extends StatefulWidget {
+  const PopupControlsPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _PopupControlsPageState();
 }

dev/integration_tests/android_semantics_testing/lib/src/tests/text_field_page.dart

@@ -10,6 +10,8 @@ export 'text_field_constants.dart';
 
 /// A page with a normal text field and a password field.
 class TextFieldPage extends StatefulWidget {
+  const TextFieldPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _TextFieldPageState();
 }

dev/integration_tests/android_views/lib/main.dart

@@ -16,10 +16,12 @@ final List<PageWidget> _allPages = <PageWidget>[
 
 void main() {
   enableFlutterDriverExtension(handler: driverDataHandler.handleMessage);
-  runApp(MaterialApp(home: Home()));
+  runApp(const MaterialApp(home: Home()));
 }
 
 class Home extends StatelessWidget {
+  const Home({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/integration_tests/android_views/lib/motion_events_page.dart

@@ -18,12 +18,12 @@ MethodChannel channel = const MethodChannel('android_views_integration');
 const String kEventsFileName = 'touchEvents';
 
 class MotionEventsPage extends PageWidget {
-  const MotionEventsPage()
-      : super('Motion Event Tests', const ValueKey<String>('MotionEventsListTile'));
+  const MotionEventsPage({Key key})
+      : super('Motion Event Tests', const ValueKey<String>('MotionEventsListTile'), key: key);
 
   @override
   Widget build(BuildContext context) {
-    return MotionEventsBody();
+    return const MotionEventsBody();
   }
 }
 
@@ -44,6 +44,8 @@ class FutureDataHandler {
 FutureDataHandler driverDataHandler = FutureDataHandler();
 
 class MotionEventsBody extends StatefulWidget {
+  const MotionEventsBody({Key key}) : super(key: key);
+
   @override
   State createState() => MotionEventsBodyState();
 }
@@ -251,7 +253,7 @@ class MotionEventsBodyState extends State<MotionEventsBody> {
 }
 
 class TouchEventDiff extends StatelessWidget {
-  const TouchEventDiff(this.originalEvent, this.synthesizedEvent);
+  const TouchEventDiff(this.originalEvent, this.synthesizedEvent, {Key key}) : super(key: key);
 
   final Map<String, dynamic> originalEvent;
   final Map<String, dynamic> synthesizedEvent;

dev/integration_tests/android_views/lib/page.dart

@@ -8,7 +8,7 @@ import 'package:flutter/material.dart';
 //
 /// A testing page has to override this in order to be put as one of the items in the main page.
 abstract class PageWidget extends StatelessWidget {
-  const PageWidget(this.title, this.tileKey);
+  const PageWidget(this.title, this.tileKey, {Key key}) : super(key: key);
 
   /// The title of the testing page
   ///

dev/integration_tests/android_views/lib/wm_integrations.dart

@@ -10,14 +10,16 @@ import 'package:flutter/services.dart';
 import 'page.dart';
 
 class WindowManagerIntegrationsPage extends PageWidget {
-  const WindowManagerIntegrationsPage()
-      : super('Window Manager Integrations Tests', const ValueKey<String>('WmIntegrationsListTile'));
+  const WindowManagerIntegrationsPage({Key key})
+      : super('Window Manager Integrations Tests', const ValueKey<String>('WmIntegrationsListTile'), key: key);
 
   @override
-  Widget build(BuildContext context) => WindowManagerBody();
+  Widget build(BuildContext context) => const WindowManagerBody();
 }
 
 class WindowManagerBody extends StatefulWidget {
+  const WindowManagerBody({Key key}) : super(key: key);
+
   @override
   State<WindowManagerBody> createState() => WindowManagerBodyState();
 }

dev/integration_tests/channels/lib/main.dart

@@ -15,10 +15,12 @@ import 'src/test_step.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(TestApp());
+  runApp(const TestApp());
 }
 
 class TestApp extends StatefulWidget {
+  const TestApp({Key key}) : super(key: key);
+
   @override
   _TestAppState createState() => _TestAppState();
 }

dev/integration_tests/external_ui/lib/main.dart

@@ -11,10 +11,12 @@ import 'package:flutter_driver/driver_extension.dart';
 void main() {
   enableFlutterDriverExtension();
   debugPrint('Application starting...');
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 class MyApp extends StatefulWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   State createState() => MyAppState();
 }

dev/integration_tests/flavors/lib/main.dart

@@ -8,10 +8,12 @@ import 'package:flutter_driver/driver_extension.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(Center(child: Flavor()));
+  runApp(const Center(child: Flavor()));
 }
 
 class Flavor extends StatefulWidget {
+  const Flavor({Key key}) : super(key: key);
+
   @override
   _FlavorState createState() => _FlavorState();
 }

dev/integration_tests/flutter_gallery/lib/demo/calculator/home.dart

@@ -138,7 +138,7 @@ class _CalculatorState extends State<Calculator> {
 }
 
 class CalcDisplay extends StatelessWidget {
-  const CalcDisplay({ this.content });
+  const CalcDisplay({ Key? key, this.content}) : super(key: key);
 
   final String? content;
 
@@ -154,7 +154,7 @@ class CalcDisplay extends StatelessWidget {
 }
 
 class KeyPad extends StatelessWidget {
-  const KeyPad({ this.calcState });
+  const KeyPad({ Key? key, this.calcState }) : super(key: key);
 
   final _CalculatorState? calcState;
 
@@ -222,7 +222,7 @@ class KeyPad extends StatelessWidget {
 }
 
 class KeyRow extends StatelessWidget {
-  const KeyRow(this.keys);
+  const KeyRow(this.keys, {Key? key}) : super(key: key);
 
   final List<Widget> keys;
 
@@ -238,7 +238,7 @@ class KeyRow extends StatelessWidget {
 }
 
 class CalcKey extends StatelessWidget {
-  const CalcKey(this.text, this.onTap);
+  const CalcKey(this.text, this.onTap, {Key? key}) : super(key: key);
 
   final String text;
   final GestureTapCallback onTap;
@@ -265,8 +265,8 @@ class CalcKey extends StatelessWidget {
 }
 
 class NumberKey extends CalcKey {
-  NumberKey(int value, _CalculatorState? calcState)
+  NumberKey(int value, _CalculatorState? calcState, {Key? key})
     : super('$value', () {
         calcState!.handleNumberTap(value);
-      });
+      }, key: key);
 }

dev/integration_tests/flutter_gallery/lib/demo/colors_demo.dart

@@ -120,6 +120,8 @@ class PaletteTabView extends StatelessWidget {
 }
 
 class ColorsDemo extends StatelessWidget {
+  const ColorsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/colors';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/contacts_demo.dart

@@ -86,6 +86,8 @@ class _ContactItem extends StatelessWidget {
 }
 
 class ContactsDemo extends StatefulWidget {
+  const ContactsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/contacts';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_activity_indicator_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoProgressIndicatorDemo extends StatelessWidget {
+  const CupertinoProgressIndicatorDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/progress_indicator';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_alert_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoAlertDemo extends StatefulWidget {
+  const CupertinoAlertDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/alert';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_buttons_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoButtonsDemo extends StatefulWidget {
+  const CupertinoButtonsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/buttons';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_navigation_demo.dart

@@ -32,13 +32,14 @@ const List<String> coolColorNames = <String>[
 const int _kChildCount = 50;
 
 class CupertinoNavigationDemo extends StatelessWidget {
-  CupertinoNavigationDemo({ this.randomSeed })
+  CupertinoNavigationDemo({ Key? key, this.randomSeed })
       : colorItems = List<Color>.generate(_kChildCount, (int index) {
           return coolColors[math.Random(randomSeed).nextInt(coolColors.length)];
         }) ,
         colorNameItems = List<String>.generate(_kChildCount, (int index) {
           return coolColorNames[math.Random(randomSeed).nextInt(coolColorNames.length)];
-        });
+        }),
+        super(key: key);
 
   static const String routeName = '/cupertino/navigation';
 
@@ -85,12 +86,12 @@ class CupertinoNavigationDemo extends StatelessWidget {
                 );
               case 1:
                 return CupertinoTabView(
-                  builder: (BuildContext context) => CupertinoDemoTab2(),
+                  builder: (BuildContext context) => const CupertinoDemoTab2(),
                   defaultTitle: 'Support Chat',
                 );
               case 2:
                 return CupertinoTabView(
-                  builder: (BuildContext context) => CupertinoDemoTab3(),
+                  builder: (BuildContext context) => const CupertinoDemoTab3(),
                   defaultTitle: 'Account',
                 );
             }
@@ -104,7 +105,7 @@ class CupertinoNavigationDemo extends StatelessWidget {
 }
 
 class ExitButton extends StatelessWidget {
-  const ExitButton();
+  const ExitButton({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -134,10 +135,11 @@ final Widget trailingButtons = Row(
 
 class CupertinoDemoTab1 extends StatelessWidget {
   const CupertinoDemoTab1({
+    Key? key,
     this.colorItems,
     this.colorNameItems,
     this.randomSeed,
-  });
+  }) : super(key: key);
 
   final List<Color>? colorItems;
   final List<String>? colorNameItems;
@@ -184,12 +186,13 @@ class CupertinoDemoTab1 extends StatelessWidget {
 
 class Tab1RowItem extends StatelessWidget {
   const Tab1RowItem({
+    Key? key,
     this.index,
     this.lastItem,
     this.color,
     this.colorName,
     this.randomSeed,
-  });
+  }) : super(key: key);
 
   final int? index;
   final bool? lastItem;
@@ -287,7 +290,7 @@ class Tab1RowItem extends StatelessWidget {
 }
 
 class Tab1ItemPage extends StatefulWidget {
-  const Tab1ItemPage({this.color, this.colorName, this.index, this.randomSeed});
+  const Tab1ItemPage({Key? key, this.color, this.colorName, this.index, this.randomSeed}) : super(key: key);
 
   final Color? color;
   final String? colorName;
@@ -441,6 +444,8 @@ class Tab1ItemPageState extends State<Tab1ItemPage> {
 }
 
 class CupertinoDemoTab2 extends StatelessWidget {
+  const CupertinoDemoTab2({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return CupertinoPageScaffold(
@@ -450,7 +455,7 @@ class CupertinoDemoTab2 extends StatelessWidget {
       child: CupertinoScrollbar(
         child: ListView(
           children: <Widget>[
-            CupertinoUserInterfaceLevel(
+            const CupertinoUserInterfaceLevel(
               data: CupertinoUserInterfaceLevelData.elevated,
               child: Tab2Header(),
             ),
@@ -463,6 +468,8 @@ class CupertinoDemoTab2 extends StatelessWidget {
 }
 
 class Tab2Header extends StatelessWidget {
+  const Tab2Header({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -589,7 +596,7 @@ enum Tab2ConversationBubbleColor {
 }
 
 class Tab2ConversationBubble extends StatelessWidget {
-  const Tab2ConversationBubble({this.text, this.color});
+  const Tab2ConversationBubble({Key? key, this.text, this.color}) : super(key: key);
 
   final String? text;
   final Tab2ConversationBubbleColor? color;
@@ -633,7 +640,7 @@ class Tab2ConversationBubble extends StatelessWidget {
 }
 
 class Tab2ConversationAvatar extends StatelessWidget {
-  const Tab2ConversationAvatar({this.text, this.color});
+  const Tab2ConversationAvatar({Key? key, this.text, this.color}) : super(key: key);
 
   final String? text;
   final Color? color;
@@ -672,7 +679,7 @@ class Tab2ConversationAvatar extends StatelessWidget {
 }
 
 class Tab2ConversationRow extends StatelessWidget {
-  const Tab2ConversationRow({this.avatar, this.text});
+  const Tab2ConversationRow({Key? key, this.avatar, this.text}) : super(key: key);
 
   final Tab2ConversationAvatar? avatar;
   final String? text;
@@ -742,6 +749,8 @@ List<Widget> buildTab2Conversation() {
 }
 
 class CupertinoDemoTab3 extends StatelessWidget {
+  const CupertinoDemoTab3({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return CupertinoPageScaffold(
@@ -755,7 +764,7 @@ class CupertinoDemoTab3 extends StatelessWidget {
               Navigator.of(context, rootNavigator: true).push(
                 CupertinoPageRoute<bool>(
                   fullscreenDialog: true,
-                  builder: (BuildContext context) => Tab3Dialog(),
+                  builder: (BuildContext context) => const Tab3Dialog(),
                 ),
               );
             },
@@ -792,6 +801,8 @@ class CupertinoDemoTab3 extends StatelessWidget {
 }
 
 class Tab3Dialog extends StatelessWidget {
+  const Tab3Dialog({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return CupertinoPageScaffold(

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_picker_demo.dart

@@ -12,6 +12,8 @@ const double _kPickerSheetHeight = 216.0;
 const double _kPickerItemHeight = 32.0;
 
 class CupertinoPickerDemo extends StatefulWidget {
+  const CupertinoPickerDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/picker';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_refresh_demo.dart

@@ -9,6 +9,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoRefreshControlDemo extends StatefulWidget {
+  const CupertinoRefreshControlDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/refresh';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_segmented_control_demo.dart

@@ -12,6 +12,8 @@ const Color _kKeyPenumbraOpacity = Color(0x24000000); // alpha = 0.14
 const Color _kAmbientShadowOpacity = Color(0x1F000000); // alpha = 0.12
 
 class CupertinoSegmentedControlDemo extends StatefulWidget {
+  const CupertinoSegmentedControlDemo({Key? key}) : super(key: key);
+
   static const String routeName = 'cupertino/segmented_control';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_slider_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoSliderDemo extends StatefulWidget {
+  const CupertinoSliderDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/slider';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_switch_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoSwitchDemo extends StatefulWidget {
+  const CupertinoSwitchDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/switch';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_text_field_demo.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/cupertino.dart';
 
 class CupertinoTextFieldDemo extends StatefulWidget {
+  const CupertinoTextFieldDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/text_fields';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/fortnightly/fortnightly.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class FortnightlyDemo extends StatelessWidget {
+  const FortnightlyDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/fortnightly';
 
   @override
@@ -15,7 +17,7 @@ class FortnightlyDemo extends StatelessWidget {
       home: Scaffold(
         body: Stack(
           children: <Widget>[
-            FruitPage(),
+            const FruitPage(),
             SafeArea(
               child: ShortAppBar(
                 onBackPressed: () {
@@ -31,7 +33,7 @@ class FortnightlyDemo extends StatelessWidget {
 }
 
 class ShortAppBar extends StatelessWidget {
-  const ShortAppBar({ this.onBackPressed });
+  const ShortAppBar({ Key? key, this.onBackPressed }) : super(key: key);
 
   final VoidCallback? onBackPressed;
 
@@ -66,6 +68,8 @@ class ShortAppBar extends StatelessWidget {
 }
 
 class FruitPage extends StatelessWidget {
+  const FruitPage({Key? key}) : super(key: key);
+
   static final String paragraph1 = '''
 Have you ever held a quince? It's strange;
 covered in a fuzz somewhere between peach skin and a spider web. And it's

dev/integration_tests/flutter_gallery/lib/demo/images_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../gallery/demo.dart';
 
 class ImagesDemo extends StatelessWidget {
+  const ImagesDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/images';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/backdrop_demo.dart

@@ -239,6 +239,8 @@ class BackdropTitle extends AnimatedWidget {
 
 // This widget is essentially the backdrop itself.
 class BackdropDemo extends StatefulWidget {
+  const BackdropDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/backdrop';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/bottom_app_bar_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class BottomAppBarDemo extends StatefulWidget {
+  const BottomAppBarDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/bottom_app_bar';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/bottom_navigation_demo.dart

@@ -74,6 +74,8 @@ class NavigationIconView {
 }
 
 class CustomIcon extends StatelessWidget {
+  const CustomIcon({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final IconThemeData iconTheme = IconTheme.of(context);
@@ -87,6 +89,8 @@ class CustomIcon extends StatelessWidget {
 }
 
 class CustomInactiveIcon extends StatelessWidget {
+  const CustomInactiveIcon({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final IconThemeData iconTheme = IconTheme.of(context);
@@ -102,6 +106,8 @@ class CustomInactiveIcon extends StatelessWidget {
 }
 
 class BottomNavigationDemo extends StatefulWidget {
+  const BottomNavigationDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/bottom_navigation';
 
   @override
@@ -125,8 +131,8 @@ class _BottomNavigationDemoState extends State<BottomNavigationDemo>
         vsync: this,
       ),
       NavigationIconView(
-        activeIcon: CustomIcon(),
-        icon: CustomInactiveIcon(),
+        activeIcon: const CustomIcon(),
+        icon: const CustomInactiveIcon(),
         title: 'Box',
         color: Colors.deepOrange,
         vsync: this,

dev/integration_tests/flutter_gallery/lib/demo/material/buttons_demo.dart

@@ -46,6 +46,8 @@ const String _actionText =
 const String _actionCode = 'buttons_action';
 
 class ButtonsDemo extends StatefulWidget {
+  const ButtonsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/buttons';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/cards_demo.dart

@@ -335,6 +335,8 @@ class TravelDestinationContent extends StatelessWidget {
 }
 
 class CardsDemo extends StatefulWidget {
+  const CardsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/cards';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/chip_demo.dart

@@ -135,6 +135,8 @@ class _ChipsTile extends StatelessWidget {
 }
 
 class ChipDemo extends StatefulWidget {
+  const ChipDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/chip';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/data_table_demo.dart

@@ -142,6 +142,8 @@ class DessertDataSource extends DataTableSource {
 }
 
 class DataTableDemo extends StatefulWidget {
+  const DataTableDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/data-table';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/date_and_time_picker_demo.dart

@@ -113,6 +113,8 @@ class _DateTimePicker extends StatelessWidget {
 }
 
 class DateAndTimePickerDemo extends StatefulWidget {
+  const DateAndTimePickerDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/date-and-time-pickers';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/dialog_demo.dart

@@ -48,6 +48,8 @@ class DialogDemoItem extends StatelessWidget {
 }
 
 class DialogDemo extends StatefulWidget {
+  const DialogDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/dialog';
 
   @override
@@ -192,7 +194,7 @@ class DialogDemoState extends State<DialogDemo> {
             child: const Text('FULLSCREEN'),
             onPressed: () {
               Navigator.push(context, MaterialPageRoute<DismissDialogAction>(
-                builder: (BuildContext context) => FullScreenDialogDemo(),
+                builder: (BuildContext context) => const FullScreenDialogDemo(),
                 fullscreenDialog: true,
               ));
             },

dev/integration_tests/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -13,6 +13,8 @@ const String _kAsset2 = 'people/square/sandra.png';
 const String _kGalleryAssetsPackage = 'flutter_gallery_assets';
 
 class DrawerDemo extends StatefulWidget {
+  const DrawerDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/drawer';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/elevation_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ElevationDemo extends StatefulWidget {
+  const ElevationDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/elevation';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/expansion_panels_demo.dart

@@ -18,11 +18,12 @@ typedef ValueToString<T> = String? Function(T value);
 
 class DualHeaderWithHint extends StatelessWidget {
   const DualHeaderWithHint({
+    Key? key,
     this.name,
     this.value,
     this.hint,
     this.showHint,
-  });
+  }) : super(key: key);
 
   final String? name;
   final String? value;
@@ -80,11 +81,12 @@ class DualHeaderWithHint extends StatelessWidget {
 
 class CollapsibleBody extends StatelessWidget {
   const CollapsibleBody({
+    Key? key,
     this.margin = EdgeInsets.zero,
     this.child,
     this.onSave,
     this.onCancel,
-  });
+  }) : super(key: key);
 
   final EdgeInsets margin;
   final Widget? child;
@@ -175,6 +177,8 @@ class DemoItem<T> {
 }
 
 class ExpansionPanelsDemo extends StatefulWidget {
+  const ExpansionPanelsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/expansion_panels';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/expansion_tile_list_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ExpansionTileListDemo extends StatelessWidget {
+  const ExpansionTileListDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/expansion-tile-list';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/full_screen_dialog_demo.dart

@@ -93,6 +93,8 @@ class DateTimeItem extends StatelessWidget {
 }
 
 class FullScreenDialogDemo extends StatefulWidget {
+  const FullScreenDialogDemo({Key? key}) : super(key: key);
+
   @override
   FullScreenDialogDemoState createState() => FullScreenDialogDemoState();
 }

dev/integration_tests/flutter_gallery/lib/demo/material/icons_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class IconsDemo extends StatefulWidget {
+  const IconsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/icons';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/modal_bottom_sheet_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ModalBottomSheetDemo extends StatelessWidget {
+  const ModalBottomSheetDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/modal-bottom-sheet';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/page_selector_demo.dart

@@ -74,6 +74,8 @@ class _PageSelector extends StatelessWidget {
 }
 
 class PageSelectorDemo extends StatelessWidget {
+  const PageSelectorDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/page-selector';
   static final List<Icon> icons = <Icon>[
     const Icon(Icons.event, semanticLabel: 'Event'),

dev/integration_tests/flutter_gallery/lib/demo/material/persistent_bottom_sheet_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class PersistentBottomSheetDemo extends StatefulWidget {
+  const PersistentBottomSheetDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/persistent-bottom-sheet';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/progress_indicator_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ProgressIndicatorDemo extends StatefulWidget {
+  const ProgressIndicatorDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/progress-indicator';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/scrollable_tabs_demo.dart

@@ -36,6 +36,8 @@ const List<_Page> _allPages = <_Page>[
 ];
 
 class ScrollableTabsDemo extends StatefulWidget {
+  const ScrollableTabsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/scrollable-tabs';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/search_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class SearchDemo extends StatefulWidget {
+  const SearchDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/search';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/selection_controls_demo.dart

@@ -28,6 +28,8 @@ const String _switchText =
 const String _switchCode = 'selectioncontrols_switch';
 
 class SelectionControlsDemo extends StatefulWidget {
+  const SelectionControlsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/selection-controls';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/slider_demo.dart

@@ -9,6 +9,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class SliderDemo extends StatefulWidget {
+  const SliderDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/slider';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/tabs_demo.dart

@@ -138,6 +138,8 @@ class _CardDataItem extends StatelessWidget {
 }
 
 class TabsDemo extends StatelessWidget {
+  const TabsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/tabs';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/tabs_fab_demo.dart

@@ -35,6 +35,8 @@ final List<_Page> _allPages = <_Page>[
 ];
 
 class TabsFabDemo extends StatefulWidget {
+  const TabsFabDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/tabs-fab';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -26,6 +26,7 @@ class PersonData {
 
 class PasswordField extends StatefulWidget {
   const PasswordField({
+    Key? key,
     this.fieldKey,
     this.hintText,
     this.labelText,
@@ -33,7 +34,7 @@ class PasswordField extends StatefulWidget {
     this.onSaved,
     this.validator,
     this.onFieldSubmitted,
-  });
+  }) : super(key: key);
 
   final Key? fieldKey;
   final String? hintText;

dev/integration_tests/flutter_gallery/lib/demo/material/tooltip_demo.dart

@@ -12,6 +12,7 @@ const String _introText =
   'apps accessible, like screen readers.';
 
 class TooltipDemo extends StatelessWidget {
+  const TooltipDemo({Key? key}) : super(key: key);
 
   static const String routeName = '/material/tooltips';
 

dev/integration_tests/flutter_gallery/lib/demo/pesto_demo.dart

@@ -10,7 +10,7 @@ class PestoDemo extends StatelessWidget {
   static const String routeName = '/pesto';
 
   @override
-  Widget build(BuildContext context) => PestoHome();
+  Widget build(BuildContext context) => const PestoHome();
 }
 
 
@@ -29,6 +29,8 @@ final ThemeData _kTheme = ThemeData(
 );
 
 class PestoHome extends StatelessWidget {
+  const PestoHome({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const RecipeGridPage(recipes: kPestoRecipes);
@@ -36,6 +38,8 @@ class PestoHome extends StatelessWidget {
 }
 
 class PestoFavorites extends StatelessWidget {
+  const PestoFavorites({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return RecipeGridPage(recipes: _favoriteRecipes.toList());
@@ -167,7 +171,7 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
   void showFavoritesPage(BuildContext context) {
     Navigator.push(context, MaterialPageRoute<void>(
       settings: const RouteSettings(name: '/pesto/favorites'),
-      builder: (BuildContext context) => PestoFavorites(),
+      builder: (BuildContext context) => const PestoFavorites(),
     ));
   }
 
@@ -185,7 +189,7 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
 }
 
 class PestoLogo extends StatefulWidget {
-  const PestoLogo({this.height, this.t});
+  const PestoLogo({Key? key, this.height, this.t}) : super(key: key);
 
   final double? height;
   final double? t;

dev/integration_tests/flutter_gallery/lib/demo/shrine/app.dart

@@ -13,6 +13,8 @@ import 'package:flutter_gallery/demo/shrine/login.dart';
 import 'package:flutter_gallery/demo/shrine/supplemental/cut_corners_border.dart';
 
 class ShrineApp extends StatefulWidget {
+  const ShrineApp({Key? key}) : super(key: key);
+
   @override
   _ShrineAppState createState() => _ShrineAppState();
 }
@@ -62,7 +64,7 @@ Route<dynamic>? _getRoute(RouteSettings settings) {
 
   return MaterialPageRoute<void>(
     settings: settings,
-    builder: (BuildContext context) => LoginPage(),
+    builder: (BuildContext context) => const LoginPage(),
     fullscreenDialog: true,
   );
 }

dev/integration_tests/flutter_gallery/lib/demo/shrine/backdrop.dart

@@ -198,12 +198,13 @@ class _BackdropTitle extends AnimatedWidget {
 /// front or back layer is showing.
 class Backdrop extends StatefulWidget {
   const Backdrop({
+    Key? key,
     required this.frontLayer,
     required this.backLayer,
     required this.frontTitle,
     required this.backTitle,
     required this.controller,
-  });
+  }) : super(key: key);
 
   final Widget frontLayer;
   final Widget backLayer;
@@ -355,7 +356,7 @@ class _BackdropState extends State<Backdrop> with SingleTickerProviderStateMixin
           onPressed: () {
             Navigator.push<void>(
               context,
-              MaterialPageRoute<void>(builder: (BuildContext context) => LoginPage()),
+              MaterialPageRoute<void>(builder: (BuildContext context) => const LoginPage()),
             );
           },
         ),
@@ -364,7 +365,7 @@ class _BackdropState extends State<Backdrop> with SingleTickerProviderStateMixin
           onPressed: () {
             Navigator.push<void>(
               context,
-              MaterialPageRoute<void>(builder: (BuildContext context) => LoginPage()),
+              MaterialPageRoute<void>(builder: (BuildContext context) => const LoginPage()),
             );
           },
         ),

dev/integration_tests/flutter_gallery/lib/demo/shrine/expanding_bottom_sheet.dart

@@ -286,9 +286,9 @@ class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with Ticker
                   width: numProducts > 3 ? _width - 94.0 : _width - 64.0,
                   height: _kCartHeight,
                   padding: const EdgeInsets.symmetric(vertical: 8.0),
-                  child: ProductThumbnailRow(),
+                  child: const ProductThumbnailRow(),
                 ),
-                ExtraProductsNumber(),
+                const ExtraProductsNumber(),
               ],
             ),
           ],
@@ -300,7 +300,7 @@ class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with Ticker
   Widget _buildShoppingCartPage() {
     return Opacity(
       opacity: _cartOpacityAnimation.value,
-      child: ShoppingCartPage(),
+      child: const ShoppingCartPage(),
     );
   }
 
@@ -404,6 +404,8 @@ class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with Ticker
 }
 
 class ProductThumbnailRow extends StatefulWidget {
+  const ProductThumbnailRow({Key? key}) : super(key: key);
+
   @override
   _ProductThumbnailRowState createState() => _ProductThumbnailRowState();
 }
@@ -511,6 +513,8 @@ class _ProductThumbnailRowState extends State<ProductThumbnailRow> {
 }
 
 class ExtraProductsNumber extends StatelessWidget {
+  const ExtraProductsNumber({Key? key}) : super(key: key);
+
   // Calculates the number to be displayed at the end of the row if there are
   // more than three products in the cart. This calculates overflow products,
   // including their duplicates (but not duplicates of products shown as
@@ -554,7 +558,7 @@ class ExtraProductsNumber extends StatelessWidget {
 }
 
 class ProductThumbnail extends StatelessWidget {
-  const ProductThumbnail(this.animation, this.opacityAnimation, this.product);
+  const ProductThumbnail(this.animation, this.opacityAnimation, this.product, {Key? key}) : super(key: key);
 
   final Animation<double> animation;
   final Animation<double> opacityAnimation;

dev/integration_tests/flutter_gallery/lib/demo/shrine/home.dart

@@ -12,7 +12,7 @@ import 'package:flutter_gallery/demo/shrine/model/product.dart';
 import 'package:flutter_gallery/demo/shrine/supplemental/asymmetric_view.dart';
 
 class ProductPage extends StatelessWidget {
-  const ProductPage({this.category = Category.all});
+  const ProductPage({Key? key, this.category = Category.all}) : super(key: key);
 
   final Category category;
 

dev/integration_tests/flutter_gallery/lib/demo/shrine/login.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter_gallery/demo/shrine/colors.dart';
 
 class LoginPage extends StatefulWidget {
+  const LoginPage({Key? key}) : super(key: key);
+
   @override
   _LoginPageState createState() => _LoginPageState();
 }

dev/integration_tests/flutter_gallery/lib/demo/shrine/shopping_cart.dart

@@ -14,6 +14,8 @@ import 'package:flutter_gallery/demo/shrine/model/product.dart';
 const double _leftColumnWidth = 60.0;
 
 class ShoppingCartPage extends StatefulWidget {
+  const ShoppingCartPage({Key? key}) : super(key: key);
+
   @override
   _ShoppingCartPageState createState() => _ShoppingCartPageState();
 }
@@ -103,7 +105,7 @@ class _ShoppingCartPageState extends State<ShoppingCartPage> {
 }
 
 class ShoppingCartSummary extends StatelessWidget {
-  const ShoppingCartSummary({this.model});
+  const ShoppingCartSummary({Key? key, this.model}) : super(key: key);
 
   final AppStateModel? model;
 
@@ -183,10 +185,11 @@ class ShoppingCartSummary extends StatelessWidget {
 
 class ShoppingCartRow extends StatelessWidget {
   const ShoppingCartRow({
+    Key? key,
     required this.product,
     required this.quantity,
     this.onPressed,
-  });
+  }) : super(key: key);
 
   final Product product;
   final int? quantity;

dev/integration_tests/flutter_gallery/lib/demo/shrine/supplemental/product_card.dart

@@ -10,8 +10,8 @@ import 'package:flutter_gallery/demo/shrine/model/app_state_model.dart';
 import 'package:flutter_gallery/demo/shrine/model/product.dart';
 
 class ProductCard extends StatelessWidget {
-  const ProductCard({ this.imageAspectRatio = 33 / 49, this.product })
-      : assert(imageAspectRatio > 0);
+  const ProductCard({ Key? key, this.imageAspectRatio = 33 / 49, this.product })
+      : assert(imageAspectRatio > 0), super(key: key);
 
   final double imageAspectRatio;
   final Product? product;

dev/integration_tests/flutter_gallery/lib/demo/shrine/supplemental/product_columns.dart

@@ -9,9 +9,10 @@ import 'package:flutter_gallery/demo/shrine/supplemental/product_card.dart';
 
 class TwoProductCardColumn extends StatelessWidget {
   const TwoProductCardColumn({
+    Key? key,
     required this.bottom,
     this.top,
-  });
+  }) : super(key: key);
 
   final Product? bottom, top;
 
@@ -57,7 +58,7 @@ class TwoProductCardColumn extends StatelessWidget {
 }
 
 class OneProductCardColumn extends StatelessWidget {
-  const OneProductCardColumn({this.product});
+  const OneProductCardColumn({Key? key, this.product}) : super(key: key);
 
   final Product? product;
 

dev/integration_tests/flutter_gallery/lib/demo/shrine_demo.dart

@@ -11,5 +11,5 @@ class ShrineDemo extends StatelessWidget {
   static const String routeName = '/shrine'; // Used by the Gallery app.
 
   @override
-  Widget build(BuildContext context) => ShrineApp();
+  Widget build(BuildContext context) => const ShrineApp();
 }

dev/integration_tests/flutter_gallery/lib/demo/transformations/transformations_demo_color_picker.dart

@@ -8,10 +8,11 @@ import 'package:flutter/material.dart';
 @immutable
 class ColorPicker extends StatelessWidget {
   const ColorPicker({
+    Key? key,
     required this.colors,
     required this.selectedColor,
     this.onColorSelection,
-  });
+  }) : super(key: key);
 
   final Set<Color> colors;
   final Color selectedColor;

dev/integration_tests/flutter_gallery/lib/demo/typography_demo.dart

@@ -39,6 +39,8 @@ class TextStyleItem extends StatelessWidget {
 }
 
 class TypographyDemo extends StatelessWidget {
+  const TypographyDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/typography';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/video_demo.dart

@@ -92,7 +92,7 @@ class VideoCard extends StatelessWidget {
 }
 
 class VideoPlayerLoading extends StatefulWidget {
-  const VideoPlayerLoading(this.controller);
+  const VideoPlayerLoading(this.controller, {Key? key}) : super(key: key);
 
   final VideoPlayerController? controller;
 
@@ -136,7 +136,7 @@ class _VideoPlayerLoadingState extends State<VideoPlayerLoading> {
 }
 
 class VideoPlayPause extends StatefulWidget {
-  const VideoPlayPause(this.controller);
+  const VideoPlayPause(this.controller, {Key? key}) : super(key: key);
 
   final VideoPlayerController? controller;
 
@@ -202,9 +202,10 @@ class _VideoPlayPauseState extends State<VideoPlayPause> {
 
 class FadeAnimation extends StatefulWidget {
   const FadeAnimation({
+    Key? key,
     this.child,
     this.duration = const Duration(milliseconds: 500),
-  });
+  }) : super(key: key);
 
   final Widget? child;
   final Duration duration;
@@ -264,9 +265,10 @@ class _FadeAnimationState extends State<FadeAnimation> with SingleTickerProvider
 
 class ConnectivityOverlay extends StatefulWidget {
   const ConnectivityOverlay({
+    Key? key,
     this.child,
     this.connectedCompleter,
-  });
+  }) : super(key: key);
 
   final Widget? child;
   final Completer<void>? connectedCompleter;

dev/integration_tests/flutter_gallery/lib/gallery/backdrop.dart

@@ -179,13 +179,14 @@ class _BackAppBar extends StatelessWidget {
 
 class Backdrop extends StatefulWidget {
   const Backdrop({
+    Key? key,
     this.frontAction,
     this.frontTitle,
     this.frontHeading,
     this.frontLayer,
     this.backTitle,
     this.backLayer,
-  });
+  }) : super(key: key);
 
   final Widget? frontAction;
   final Widget? frontTitle;

dev/integration_tests/flutter_gallery/lib/gallery/demo.dart

@@ -42,12 +42,13 @@ class ComponentDemoTabData {
 
 class TabbedComponentDemoScaffold extends StatelessWidget {
   const TabbedComponentDemoScaffold({
+    Key? key,
     this.title,
     this.demos,
     this.actions,
     this.isScrollable = true,
     this.showExampleCodeAction = true,
-  });
+  }) : super(key: key);
 
   final List<ComponentDemoTabData>? demos;
   final String? title;
@@ -147,7 +148,7 @@ class TabbedComponentDemoScaffold extends StatelessWidget {
 }
 
 class FullScreenCodeDialog extends StatefulWidget {
-  const FullScreenCodeDialog({ this.exampleCodeTag });
+  const FullScreenCodeDialog({ Key? key, this.exampleCodeTag }) : super(key: key);
 
   final String? exampleCodeTag;