Remove unused generic type from BottomSheet (#137791)

Fixes https://github.com/flutter/flutter/issues/137424.

The generic type argument was unused.

dev/benchmarks/macrobenchmarks/lib/src/web/material3.dart

@@ -1579,7 +1579,7 @@ class BottomSheetSection extends StatefulWidget {
 
 class _BottomSheetSectionState extends State<BottomSheetSection> {
   bool isNonModalBottomSheetOpen = false;
-  PersistentBottomSheetController<void>? _nonModalBottomSheetController;
+  PersistentBottomSheetController? _nonModalBottomSheetController;
 
   @override
   Widget build(BuildContext context) {
@@ -1663,7 +1663,7 @@ class _BottomSheetSectionState extends State<BottomSheetSection> {
                 });
               }
 
-              _nonModalBottomSheetController = showBottomSheet<void>(
+              _nonModalBottomSheetController = showBottomSheet(
                 elevation: 8.0,
                 context: context,
                 constraints: const BoxConstraints(maxWidth: 640),

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

@@ -265,7 +265,7 @@ class StockHomeState extends State<StockHome> {
         Navigator.pushNamed(context, '/stock', arguments: stock.symbol);
       },
       onShow: (Stock stock) {
-        _scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) => StockSymbolBottomSheet(stock: stock));
+        _scaffoldKey.currentState!.showBottomSheet((BuildContext context) => StockSymbolBottomSheet(stock: stock));
       },
     );
   }

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

@@ -32,7 +32,7 @@ class ListDemo extends StatefulWidget {
 class _ListDemoState extends State<ListDemo> {
   static final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
 
-  PersistentBottomSheetController<void>? _bottomSheet;
+  PersistentBottomSheetController? _bottomSheet;
   _MaterialListType? _itemType = _MaterialListType.threeLine;
   bool? _dense = false;
   bool? _showAvatars = true;
@@ -51,7 +51,7 @@ class _ListDemoState extends State<ListDemo> {
   }
 
   void _showConfigurationSheet() {
-    final PersistentBottomSheetController<void> bottomSheet = scaffoldKey.currentState!.showBottomSheet<void>((BuildContext bottomSheetContext) {
+    final PersistentBottomSheetController bottomSheet = scaffoldKey.currentState!.showBottomSheet((BuildContext bottomSheetContext) {
       return Container(
         decoration: const BoxDecoration(
           border: Border(top: BorderSide(color: Colors.black26)),

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

@@ -30,7 +30,7 @@ class _PersistentBottomSheetDemoState extends State<PersistentBottomSheetDemo> {
     setState(() { // disable the button
       _showBottomSheetCallback = null;
     });
-    _scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    _scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       final ThemeData themeData = Theme.of(context);
       return Container(
         decoration: BoxDecoration(

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

@@ -37,7 +37,7 @@ class _ListItem {
 class _ListDemoState extends State<ReorderableListDemo> {
   static final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
 
-  PersistentBottomSheetController<void>? _bottomSheet;
+  PersistentBottomSheetController? _bottomSheet;
   _ReorderableListType? _itemType = _ReorderableListType.threeLine;
   bool? _reverse = false;
   bool _reverseSort = false;
@@ -71,7 +71,7 @@ class _ListDemoState extends State<ReorderableListDemo> {
 
   void _showConfigurationSheet() {
     setState(() {
-      _bottomSheet = scaffoldKey.currentState!.showBottomSheet<void>((BuildContext bottomSheetContext) {
+      _bottomSheet = scaffoldKey.currentState!.showBottomSheet((BuildContext bottomSheetContext) {
         return DecoratedBox(
           decoration: const BoxDecoration(
             border: Border(top: BorderSide(color: Colors.black26)),

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

@@ -71,7 +71,7 @@ class _TabsFabDemoState extends State<TabsFabDemo> with SingleTickerProviderStat
   }
 
   void _showExplanatoryText() {
-    _scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    _scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return Container(
         decoration: BoxDecoration(
           border: Border(top: BorderSide(color: Theme.of(context).dividerColor))

examples/api/lib/material/navigation_bar/navigation_bar.2.dart

@@ -220,7 +220,7 @@ class RootPage extends StatelessWidget {
                 return ElevatedButton(
                   style: buttonStyle,
                   onPressed: () {
-                    showBottomSheet<void>(
+                    showBottomSheet(
                       context: context,
                       builder: (BuildContext context) {
                         return Container(

examples/api/lib/material/scaffold/scaffold.of.0.dart

@@ -36,7 +36,7 @@ class MyScaffoldBody extends StatelessWidget {
       child: ElevatedButton(
         child: const Text('SHOW BOTTOM SHEET'),
         onPressed: () {
-          Scaffold.of(context).showBottomSheet<void>(
+          Scaffold.of(context).showBottomSheet(
             (BuildContext context) {
               return Container(
                 alignment: Alignment.center,

examples/api/lib/material/scaffold/scaffold.of.1.dart

@@ -34,7 +34,7 @@ class OfExample extends StatelessWidget {
             child: ElevatedButton(
               child: const Text('SHOW BOTTOM SHEET'),
               onPressed: () {
-                Scaffold.of(context).showBottomSheet<void>(
+                Scaffold.of(context).showBottomSheet(
                   (BuildContext context) {
                     return Container(
                       alignment: Alignment.center,

examples/api/lib/material/scaffold/scaffold_state.show_bottom_sheet.0.dart

@@ -31,7 +31,7 @@ class ShowBottomSheetExample extends StatelessWidget {
       child: ElevatedButton(
         child: const Text('showBottomSheet'),
         onPressed: () {
-          Scaffold.of(context).showBottomSheet<void>(
+          Scaffold.of(context).showBottomSheet(
             (BuildContext context) {
               return Container(
                 height: 200,

packages/flutter/lib/src/material/bottom_sheet.dart

@@ -1324,7 +1324,7 @@ Future<T?> showModalBottomSheet<T>({
 ///  * [Scaffold.of], for information about how to obtain the [BuildContext].
 ///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
 ///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
-PersistentBottomSheetController<T> showBottomSheet<T>({
+PersistentBottomSheetController showBottomSheet({
   required BuildContext context,
   required WidgetBuilder builder,
   Color? backgroundColor,
@@ -1337,7 +1337,7 @@ PersistentBottomSheetController<T> showBottomSheet<T>({
 }) {
   assert(debugCheckHasScaffold(context));
 
-  return Scaffold.of(context).showBottomSheet<T>(
+  return Scaffold.of(context).showBottomSheet(
     builder,
     backgroundColor: backgroundColor,
     elevation: elevation,

packages/flutter/lib/src/material/scaffold.dart

@@ -2121,7 +2121,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
   /// appropriate [IconButton], and handles the edge-swipe gesture, to show the
   /// drawer.
   ///
-  /// To close the drawer, use either [ScaffoldState.closeEndDrawer] or
+  /// To close the drawer, use either [ScaffoldState.closeDrawer] or
   /// [Navigator.pop].
   ///
   /// See [Scaffold.of] for information about how to obtain the [ScaffoldState].
@@ -2196,7 +2196,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
   // Important if the app/user takes an action that could repeatedly show a
   // bottom sheet.
   final List<_StandardBottomSheet> _dismissedBottomSheets = <_StandardBottomSheet>[];
-  PersistentBottomSheetController<dynamic>? _currentBottomSheet;
+  PersistentBottomSheetController? _currentBottomSheet;
   final GlobalKey _currentBottomSheetKey = GlobalKey();
   LocalHistoryEntry? _persistentSheetHistoryEntry;
 
@@ -2234,7 +2234,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
         assert(_dismissedBottomSheets.isEmpty);
       }
 
-      _currentBottomSheet = _buildBottomSheet<void>(
+      _currentBottomSheet = _buildBottomSheet(
         (BuildContext context) {
           return NotificationListener<DraggableScrollableNotification>(
             onNotification: persistentBottomSheetExtentChanged,
@@ -2290,7 +2290,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
     _currentBottomSheetKey.currentState!.setState(() {});
   }
 
-  PersistentBottomSheetController<T> _buildBottomSheet<T>(
+  PersistentBottomSheetController _buildBottomSheet(
     WidgetBuilder builder, {
     required bool isPersistent,
     required AnimationController animationController,
@@ -2313,7 +2313,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
       return true;
     }());
 
-    final Completer<T> completer = Completer<T>();
+    final Completer<void> completer = Completer<void>();
     final GlobalKey<_StandardBottomSheetState> bottomSheetKey = GlobalKey<_StandardBottomSheetState>();
     late _StandardBottomSheet bottomSheet;
 
@@ -2351,10 +2351,6 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
       if (animationController.status != AnimationStatus.dismissed) {
         _dismissedBottomSheets.add(bottomSheet);
       }
-      // TODO(srawlins): Ensure that this Completer has a nullable type (or more
-      // likely, `void`).
-      // https://github.com/flutter/flutter/issues/137294).
-      // ignore: null_argument_to_non_null_type
       completer.complete();
     }
 
@@ -2412,7 +2408,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
       ModalRoute.of(context)!.addLocalHistoryEntry(entry!);
     }
 
-    return PersistentBottomSheetController<T>._(
+    return PersistentBottomSheetController._(
       bottomSheet,
       completer,
       entry != null
@@ -2471,7 +2467,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
   ///  * [Scaffold.of], for information about how to obtain the [ScaffoldState].
   ///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
   ///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
-  PersistentBottomSheetController<T> showBottomSheet<T>(
+  PersistentBottomSheetController showBottomSheet(
     WidgetBuilder builder, {
     Color? backgroundColor,
     double? elevation,
@@ -2496,7 +2492,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
     _closeCurrentBottomSheet();
     final AnimationController controller = (transitionAnimationController ?? BottomSheet.createAnimationController(this))..forward();
     setState(() {
-      _currentBottomSheet = _buildBottomSheet<T>(
+      _currentBottomSheet = _buildBottomSheet(
         builder,
         isPersistent: false,
         animationController: controller,
@@ -2509,7 +2505,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
         shouldDisposeAnimationController: transitionAnimationController == null,
       );
     });
-    return _currentBottomSheet! as PersistentBottomSheetController<T>;
+    return _currentBottomSheet!;
   }
 
   // Floating Action Button API
@@ -3274,7 +3270,7 @@ class _StandardBottomSheetState extends State<_StandardBottomSheet> {
 /// This controller is used to display both standard and persistent bottom
 /// sheets. A bottom sheet is only persistent if it is set as the
 /// [Scaffold.bottomSheet].
-class PersistentBottomSheetController<T> extends ScaffoldFeatureController<_StandardBottomSheet, T> {
+class PersistentBottomSheetController extends ScaffoldFeatureController<_StandardBottomSheet, void> {
   const PersistentBottomSheetController._(
     super.widget,
     super.completer,

packages/flutter/lib/src/widgets/framework.dart

@@ -2178,7 +2178,7 @@ typedef ConditionalElementVisitor = bool Function(Element element);
 ///         return TextButton(
 ///           child: const Text('BUTTON'),
 ///           onPressed: () {
-///             Scaffold.of(context).showBottomSheet<void>(
+///             Scaffold.of(context).showBottomSheet(
 ///               (BuildContext context) {
 ///                 return Container(
 ///                   alignment: Alignment.center,

packages/flutter/test/material/bottom_sheet_test.dart

@@ -106,7 +106,7 @@ void main() {
     expect(showBottomSheetThenCalled, isFalse);
     expect(find.text('BottomSheet'), findsNothing);
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return const SizedBox(
         height: 200.0,
         child:  Text('BottomSheet'),
@@ -141,7 +141,7 @@ void main() {
     expect(showBottomSheetThenCalled, isFalse);
     expect(find.text('BottomSheet'), findsNothing);
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return const SizedBox(
         height: 200.0,
         child: Text('BottomSheet'),
@@ -178,7 +178,7 @@ void main() {
     expect(showBottomSheetThenCalled, isFalse);
     expect(find.text('BottomSheet'), findsNothing);
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return const SizedBox(
         height: 200.0,
         child: Text('BottomSheet'),
@@ -216,7 +216,7 @@ void main() {
     expect(buildCount, 0);
     expect(find.text('BottomSheet'), findsNothing);
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       buildCount++;
       return const SizedBox(
         height: 200.0,
@@ -618,7 +618,7 @@ void main() {
     expect(showBottomSheetThenCalled, isFalse);
     expect(find.text('BottomSheet'), findsNothing);
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return Container(
         margin: const EdgeInsets.all(40.0),
         child: const Text('BottomSheet'),
@@ -672,7 +672,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return Container(
         margin: const EdgeInsets.all(40.0),
         child: const Text('BottomSheet'),
@@ -1482,7 +1482,7 @@ void main() {
             return GestureDetector(
               key: tapTarget,
               onTap: () {
-                showBottomSheet<void>(
+                showBottomSheet(
                   context: context,
                   // The default duration and reverseDuration is 1 second
                   transitionAnimationController: controller,
@@ -1539,7 +1539,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    scaffoldKey.currentState!.showBottomSheet((_) {
       return Builder(
         builder: (BuildContext context) {
           return Container(height: 200.0);
@@ -1553,7 +1553,7 @@ void main() {
     // The first sheet's animation is still running.
 
     // Trigger the second sheet will remove the first sheet from tree.
-    scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    scaffoldKey.currentState!.showBottomSheet((_) {
       return Builder(
         builder: (BuildContext context) {
           return Container(height: 200.0);
@@ -1575,7 +1575,7 @@ void main() {
   // Regression test for https://github.com/flutter/flutter/issues/99627
   testWidgetsWithLeakTracking('The old route entry should be removed when a new sheet popup', (WidgetTester tester) async {
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey();
-    PersistentBottomSheetController<void>? sheetController;
+    PersistentBottomSheetController? sheetController;
 
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(
@@ -1587,7 +1587,7 @@ void main() {
     final ModalRoute<dynamic> route = ModalRoute.of(scaffoldKey.currentContext!)!;
     expect(route.canPop, false);
 
-    scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    scaffoldKey.currentState!.showBottomSheet((_) {
       return Builder(
         builder: (BuildContext context) {
           return Container(height: 200.0);
@@ -1600,7 +1600,7 @@ void main() {
     expect(route.canPop, true);
 
     // Trigger the second sheet will remove the first sheet from tree.
-    sheetController = scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    sheetController = scaffoldKey.currentState!.showBottomSheet((_) {
       return Builder(
         builder: (BuildContext context) {
           return Container(height: 200.0);
@@ -1632,7 +1632,7 @@ void main() {
             return GestureDetector(
               key: tapTarget,
               onTap: () {
-                showBottomSheet<void>(
+                showBottomSheet(
                   context: context,
                   transitionAnimationController: controller,
                   builder: (BuildContext context) {
@@ -1675,7 +1675,7 @@ void main() {
 
   testWidgetsWithLeakTracking('Calling PersistentBottomSheetController.close does not crash when it is not the current bottom sheet', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/93717
-    PersistentBottomSheetController<void>? sheetController1;
+    PersistentBottomSheetController? sheetController1;
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(
         body: Builder(builder: (BuildContext context) {
@@ -1685,7 +1685,7 @@ void main() {
                 ElevatedButton(
                   child: const Text('show 1'),
                   onPressed: () {
-                    sheetController1 = Scaffold.of(context).showBottomSheet<void>(
+                    sheetController1 = Scaffold.of(context).showBottomSheet(
                       (BuildContext context) => const Text('BottomSheet 1'),
                     );
                   },
@@ -1693,7 +1693,7 @@ void main() {
                 ElevatedButton(
                   child: const Text('show 2'),
                   onPressed: () {
-                    Scaffold.of(context).showBottomSheet<void>(
+                    Scaffold.of(context).showBottomSheet(
                       (BuildContext context) => const Text('BottomSheet 2'),
                     );
                   },
@@ -1914,7 +1914,7 @@ void main() {
               child: ElevatedButton(
                 child: const Text('Press me'),
                 onPressed: () {
-                  Scaffold.of(context).showBottomSheet<void>(
+                  Scaffold.of(context).showBottomSheet(
                     (BuildContext context) => const Text('BottomSheet'),
                   );
                 },
@@ -2033,7 +2033,7 @@ void main() {
               child: ElevatedButton(
                 child: const Text('Press me'),
                 onPressed: () {
-                  Scaffold.of(context).showBottomSheet<void>(
+                  Scaffold.of(context).showBottomSheet(
                     (BuildContext context) => const Text('BottomSheet'),
                   );
                 },
@@ -2102,7 +2102,7 @@ void main() {
               child: ElevatedButton(
                 child: const Text('Press me'),
                 onPressed: () {
-                  Scaffold.of(context).showBottomSheet<void>(
+                  Scaffold.of(context).showBottomSheet(
                     (BuildContext context) => const Text('BottomSheet'),
                     constraints: const BoxConstraints(maxWidth: sheetMaxWidth),
                   );

packages/flutter/test/material/bottom_sheet_theme_test.dart

@@ -397,7 +397,7 @@ Widget bottomSheetWithElevations(BottomSheetThemeData bottomSheetTheme, {bool us
                 RawMaterialButton(
                   child: const Text('Show Persistent'),
                   onPressed: () {
-                    showBottomSheet<void>(
+                    showBottomSheet(
                       context: context,
                       builder: (BuildContext _) {
                         return const Text(

packages/flutter/test/material/debug_test.dart

@@ -97,7 +97,7 @@ void main() {
         ),
         home: Builder(
           builder: (BuildContext context) {
-            showBottomSheet<void>(
+            showBottomSheet(
               context: context,
               builder: (BuildContext context) => Container(),
             );

packages/flutter/test/material/persistent_bottom_sheet_test.dart

@@ -107,7 +107,7 @@ void main() {
       ),
     ));
 
-    final PersistentBottomSheetController<void> bottomSheet = scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    final PersistentBottomSheetController bottomSheet = scaffoldKey.currentState!.showBottomSheet((_) {
       return Builder(
         builder: (BuildContext context) {
           buildCount += 1;
@@ -164,7 +164,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return ListView(
         shrinkWrap: true,
         primary: false,
@@ -196,7 +196,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return DraggableScrollableSheet(
         expand: false,
         shouldCloseOnMinExtent: false,
@@ -234,7 +234,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return ListView(
         shrinkWrap: true,
         primary: false,
@@ -269,7 +269,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>(
+    scaffoldKey.currentState!.showBottomSheet(
       (BuildContext context) {
         return DraggableScrollableSheet(
           expand: false,
@@ -423,7 +423,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>(
+    scaffoldKey.currentState!.showBottomSheet(
       (BuildContext context) {
         return DraggableScrollableSheet(
           expand: false,
@@ -472,7 +472,7 @@ void main() {
     ));
 
     int buildCount = 0;
-    showBottomSheet<void>(
+    showBottomSheet(
       context: key.currentContext!,
       builder: (BuildContext context) {
         return Builder(
@@ -510,7 +510,7 @@ void main() {
 
     await tester.pump();
 
-    showBottomSheet<void>(
+    showBottomSheet(
       context: scaffoldContext,
       builder: (BuildContext context) {
         bottomSheetContext = context;
@@ -627,7 +627,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return ListView(
         shrinkWrap: true,
         primary: false,
@@ -657,7 +657,7 @@ void main() {
       ),
     ));
 
-    final PersistentBottomSheetController<void> bottomSheet = scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    final PersistentBottomSheetController bottomSheet = scaffoldKey.currentState!.showBottomSheet((_) {
       return Builder(
         builder: (BuildContext context) {
           return Container(height: 200.0);

packages/flutter/test/material/scaffold_test.dart

@@ -596,7 +596,7 @@ void main() {
             builder: (BuildContext context) {
               return GestureDetector(
                 onTap: () {
-                  Scaffold.of(context).showBottomSheet<void>((BuildContext context) {
+                  Scaffold.of(context).showBottomSheet((BuildContext context) {
                     return Container(
                       key: sheetKey,
                       color: Colors.blue[500],
@@ -2173,7 +2173,7 @@ void main() {
         );
         late FlutterError error;
         try {
-          key.currentState!.showBottomSheet<void>((BuildContext context) {
+          key.currentState!.showBottomSheet((BuildContext context) {
             final ThemeData themeData = Theme.of(context);
             return Container(
               decoration: BoxDecoration(
@@ -2234,7 +2234,7 @@ void main() {
             ),
           ),
         );
-        key.currentState!.showBottomSheet<void>((_) => Container());
+        key.currentState!.showBottomSheet((_) => Container());
         await tester.tap(find.byKey(buttonKey));
         await tester.pump();
         expect(errors, isNotEmpty);
@@ -2266,7 +2266,7 @@ void main() {
         MaterialApp(
           home: Builder(
             builder: (BuildContext context) {
-              Scaffold.of(context).showBottomSheet<void>((BuildContext context) {
+              Scaffold.of(context).showBottomSheet((BuildContext context) {
                 return Container();
               });
               return Container();
@@ -2766,7 +2766,7 @@ void main() {
     final DraggableScrollableController draggableController = DraggableScrollableController();
     addTearDown(draggableController.dispose);
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey();
-    PersistentBottomSheetController<void>? sheetController;
+    PersistentBottomSheetController? sheetController;
 
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(
@@ -2775,7 +2775,7 @@ void main() {
       ),
     ));
 
-    sheetController = scaffoldKey.currentState!.showBottomSheet<void>((_) {
+    sheetController = scaffoldKey.currentState!.showBottomSheet((_) {
       return DraggableScrollableSheet(
         expand: false,
         controller: draggableController,
@@ -2811,7 +2811,7 @@ void main() {
 
   testWidgetsWithLeakTracking("Closing bottom sheet & removing FAB at the same time doesn't throw assertion", (WidgetTester tester) async {
       final Key bottomSheetKey = UniqueKey();
-      PersistentBottomSheetController<void>? controller;
+      PersistentBottomSheetController? controller;
       bool show = true;
 
       await tester.pumpWidget(StatefulBuilder(

packages/flutter/test/widgets/page_transitions_test.dart

@@ -28,7 +28,7 @@ class PersistentBottomSheetTestState extends State<PersistentBottomSheetTest> {
   bool setStateCalled = false;
 
   void showBottomSheet() {
-    _scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
+    _scaffoldKey.currentState!.showBottomSheet((BuildContext context) {
       return const Text('bottomSheet');
     })
     .closed.whenComplete(() {