Use wildcards (#161548)

https://dart.dev/language/pattern-types#wildcard

examples/api/lib/services/text_input/text_input_control.0.dart

@@ -92,7 +92,7 @@ class MyVirtualKeyboardState extends State<MyVirtualKeyboard> {
   Widget build(BuildContext context) {
     return ValueListenableBuilder<bool>(
       valueListenable: _inputControl.visible,
-      builder: (_, bool visible, __) {
+      builder: (_, bool visible, _) {
         return Visibility(
           visible: visible,
           child: FocusScope(

examples/api/lib/widgets/magnifier/cupertino_text_magnifier.0.dart

@@ -39,7 +39,7 @@ class _CupertinoTextMagnifierExampleAppState extends State<CupertinoTextMagnifie
         child: Center(
           child: CupertinoTextField(
             magnifierConfiguration: TextMagnifierConfiguration(
-              magnifierBuilder: (_, __, ValueNotifier<MagnifierInfo> magnifierInfo) {
+              magnifierBuilder: (_, _, ValueNotifier<MagnifierInfo> magnifierInfo) {
                 return CupertinoTextMagnifier(
                   controller: _controller,
                   magnifierInfo: magnifierInfo,

examples/api/lib/widgets/scroll_position/scroll_controller_notification.0.dart

@@ -73,7 +73,7 @@ class _ScrollNotificationDemoState extends State<ScrollNotificationDemo> {
               child: Text('Item $index'),
             );
           },
-          separatorBuilder: (_, __) => const Divider(indent: 20, endIndent: 20, thickness: 2),
+          separatorBuilder: (_, _) => const Divider(indent: 20, endIndent: 20, thickness: 2),
         ),
       ],
     );

examples/api/lib/widgets/text_magnifier/text_magnifier.0.dart

@@ -31,7 +31,7 @@ class TextMagnifierExampleApp extends StatelessWidget {
               // this `TextField` will use to build a magnifier with.
               magnifierConfiguration: TextMagnifierConfiguration(
                 magnifierBuilder:
-                    (_, __, ValueNotifier<MagnifierInfo> magnifierInfo) =>
+                    (_, _, ValueNotifier<MagnifierInfo> magnifierInfo) =>
                         CustomMagnifier(magnifierInfo: magnifierInfo),
               ),
               controller: TextEditingController(text: text),