Add maybeOf for all the cases where of returns nullable. (#114120)

Author: gspencergoog

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

@@ -210,8 +210,8 @@ class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {
               builder: (BuildContext context) {
                 return CollapsibleBody(
                   margin: const EdgeInsets.symmetric(horizontal: 16.0),
-                  onSave: () { Form.of(context)!.save(); close(); },
-                  onCancel: () { Form.of(context)!.reset(); close(); },
+                  onSave: () { Form.of(context).save(); close(); },
+                  onCancel: () { Form.of(context).reset(); close(); },
                   child: Padding(
                     padding: const EdgeInsets.symmetric(horizontal: 16.0),
                     child: TextFormField(
@@ -244,8 +244,8 @@ class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {
             child: Builder(
               builder: (BuildContext context) {
                 return CollapsibleBody(
-                  onSave: () { Form.of(context)!.save(); close(); },
-                  onCancel: () { Form.of(context)!.reset(); close(); },
+                  onSave: () { Form.of(context).save(); close(); },
+                  onCancel: () { Form.of(context).reset(); close(); },
                   child: FormField<Location>(
                     initialValue: item.value,
                     onSaved: (Location? result) { item.value = result; },
@@ -298,8 +298,8 @@ class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {
             child: Builder(
               builder: (BuildContext context) {
                 return CollapsibleBody(
-                  onSave: () { Form.of(context)!.save(); close(); },
-                  onCancel: () { Form.of(context)!.reset(); close(); },
+                  onSave: () { Form.of(context).save(); close(); },
+                  onCancel: () { Form.of(context).reset(); close(); },
                   child: FormField<double>(
                     initialValue: item.value,
                     onSaved: (double? value) { item.value = value; },

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

@@ -12,15 +12,15 @@ class _PageSelector extends StatelessWidget {
   final List<Icon>? icons;
 
   void _handleArrowButtonPress(BuildContext context, int delta) {
-    final TabController controller = DefaultTabController.of(context)!;
+    final TabController controller = DefaultTabController.of(context);
     if (!controller.indexIsChanging) {
       controller.animateTo((controller.index + delta).clamp(0, icons!.length - 1));
     }
   }
 
   @override
   Widget build(BuildContext context) {
-    final TabController? controller = DefaultTabController.of(context);
+    final TabController? controller = DefaultTabController.maybeOf(context);
     final Color color = Theme.of(context).colorScheme.secondary;
     return SafeArea(
       top: false,

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

@@ -63,7 +63,7 @@ class TabbedComponentDemoScaffold extends StatefulWidget {
 
 class _TabbedComponentDemoScaffoldState extends State<TabbedComponentDemoScaffold> {
   void _showExampleCode(BuildContext context) {
-    final String? tag = widget.demos![DefaultTabController.of(context)!.index].exampleCodeTag;
+    final String? tag = widget.demos![DefaultTabController.of(context).index].exampleCodeTag;
     if (tag != null) {
       Navigator.push(context, MaterialPageRoute<FullScreenCodeDialog>(
         builder: (BuildContext context) => FullScreenCodeDialog(exampleCodeTag: tag)
@@ -72,7 +72,7 @@ class _TabbedComponentDemoScaffoldState extends State<TabbedComponentDemoScaffol
   }
 
   Future<void> _showApiDocumentation(BuildContext context) async {
-    final String? url = widget.demos![DefaultTabController.of(context)!.index].documentationUrl;
+    final String? url = widget.demos![DefaultTabController.of(context).index].documentationUrl;
     if (url == null) {
       return;
     }

dev/manual_tests/lib/material_arc.dart

@@ -451,7 +451,7 @@ class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateM
             return FloatingActionButton(
               child: const Icon(Icons.refresh),
               onPressed: () {
-                _play(_allDemos[DefaultTabController.of(context)!.index]);
+                _play(_allDemos[DefaultTabController.of(context).index]);
               },
             );
           },

dev/manual_tests/lib/overlay_geometry.dart

@@ -172,8 +172,8 @@ class OverlayGeometryAppState extends State<OverlayGeometryApp> {
       markers[MarkerType.topLeft] = box!.localToGlobal(Offset.zero);
       final Size size = box.size;
       markers[MarkerType.bottomRight] = box.localToGlobal(Offset(size.width, size.height));
-      final ScrollableState? scrollable = Scrollable.of(target.currentContext!);
-      markersScrollOffset = scrollable!.position.pixels;
+      final ScrollableState scrollable = Scrollable.of(target.currentContext!);
+      markersScrollOffset = scrollable.position.pixels;
     });
   }
 

examples/api/lib/cupertino/text_form_field_row/cupertino_text_form_field_row.1.dart

@@ -34,7 +34,7 @@ class FromSectionExample extends StatelessWidget {
         child: Form(
           autovalidateMode: AutovalidateMode.always,
           onChanged: () {
-            Form.of(primaryFocus!.context!)?.save();
+            Form.maybeOf(primaryFocus!.context!)?.save();
           },
           child: CupertinoFormSection.insetGrouped(
             header: const Text('SECTION 1'),

examples/api/lib/material/tab_controller/tab_controller.1.dart

@@ -38,7 +38,7 @@ class MyStatelessWidget extends StatelessWidget {
       // The Builder widget is used to have a different BuildContext to access
       // closest DefaultTabController.
       child: Builder(builder: (BuildContext context) {
-        final TabController tabController = DefaultTabController.of(context)!;
+        final TabController tabController = DefaultTabController.of(context);
         tabController.addListener(() {
           if (!tabController.indexIsChanging) {
             // Your code goes here.

examples/api/lib/material/text_form_field/text_form_field.1.dart

@@ -44,7 +44,7 @@ class _MyStatefulWidgetState extends State<MyStatefulWidget> {
             child: Form(
               autovalidateMode: AutovalidateMode.always,
               onChanged: () {
-                Form.of(primaryFocus!.context!)!.save();
+                Form.of(primaryFocus!.context!).save();
               },
               child: Wrap(
                 children: List<Widget>.generate(5, (int index) {

packages/flutter/lib/src/cupertino/page_scaffold.dart

@@ -90,7 +90,7 @@ class CupertinoPageScaffold extends StatefulWidget {
 class _CupertinoPageScaffoldState extends State<CupertinoPageScaffold> {
 
   void _handleStatusBarTap() {
-    final ScrollController? primaryScrollController = PrimaryScrollController.of(context);
+    final ScrollController? primaryScrollController = PrimaryScrollController.maybeOf(context);
     // Only act on the scroll controller if it has any attached scroll positions.
     if (primaryScrollController != null && primaryScrollController.hasClients) {
       primaryScrollController.animateTo(

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

@@ -602,7 +602,7 @@ class _PackagesViewState extends State<_PackagesView> {
     }
     final String packageName = data.packages[widget.selectedId.value ?? 0];
     final List<int> bindings = data.packageLicenseBindings[packageName]!;
-    _MasterDetailFlow.of(context)!.setInitialDetailPage(
+    _MasterDetailFlow.of(context).setInitialDetailPage(
       _DetailArguments(
         packageName,
         bindings.map((int i) => data.licenses[i]).toList(growable: false),
@@ -632,7 +632,7 @@ class _PackagesViewState extends State<_PackagesView> {
           numberLicenses: bindings.length,
           onTap: () {
             widget.selectedId.value = packageIndex;
-            _MasterDetailFlow.of(context)!.openDetailPage(_DetailArguments(
+            _MasterDetailFlow.of(context).openDetailPage(_DetailArguments(
               packageName,
               bindings.map((int i) => data.licenses[i]).toList(growable: false),
             ));
@@ -1073,7 +1073,7 @@ class _MasterDetailFlow extends StatefulWidget {
   // ```dart
   // _MasterDetailFlow.of(context).openDetailPage(arguments);
   // ```
-  static _MasterDetailFlowProxy? of(BuildContext context) {
+  static _MasterDetailFlowProxy of(BuildContext context) {
     _PageOpener? pageOpener = context.findAncestorStateOfType<_MasterDetailScaffoldState>();
     pageOpener ??= context.findAncestorStateOfType<_MasterDetailFlowState>();
     assert(() {
@@ -1086,7 +1086,7 @@ class _MasterDetailFlow extends StatefulWidget {
       }
       return true;
     }());
-    return pageOpener != null ? _MasterDetailFlowProxy._(pageOpener) : null;
+    return _MasterDetailFlowProxy._(pageOpener!);
   }
 }
 
@@ -1339,13 +1339,13 @@ class _MasterDetailScaffoldState extends State<_MasterDetailScaffold>
   @override
   void openDetailPage(Object arguments) {
     SchedulerBinding.instance.addPostFrameCallback((_) => _detailArguments.value = arguments);
-    _MasterDetailFlow.of(context)!.openDetailPage(arguments);
+    _MasterDetailFlow.of(context).openDetailPage(arguments);
   }
 
   @override
   void setInitialDetailPage(Object arguments) {
     SchedulerBinding.instance.addPostFrameCallback((_) => _detailArguments.value = arguments);
-    _MasterDetailFlow.of(context)!.setInitialDetailPage(arguments);
+    _MasterDetailFlow.of(context).setInitialDetailPage(arguments);
   }
 
   @override