Adds `CheckboxListTile.checkboxShape` (#95714)

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

@@ -137,6 +137,7 @@ class CheckboxListTile extends StatelessWidget {
     this.contentPadding,
     this.tristate = false,
     this.shape,
+    this.checkboxShape,
     this.selectedTileColor,
     this.side,
     this.visualDensity,
@@ -256,6 +257,13 @@ class CheckboxListTile extends StatelessWidget {
   /// {@macro flutter.material.ListTile.shape}
   final ShapeBorder? shape;
 
+  /// {@macro flutter.material.checkbox.shape}
+  ///
+  /// If this property is null then [CheckboxThemeData.shape] of [ThemeData.checkboxTheme]
+  /// is used. If that's null then the shape will be a [RoundedRectangleBorder]
+  /// with a circular corner radius of 1.0.
+  final OutlinedBorder? checkboxShape;
+
   /// If non-null, defines the background color when [CheckboxListTile.selected] is true.
   final Color? selectedTileColor;
 
@@ -308,6 +316,7 @@ class CheckboxListTile extends StatelessWidget {
       materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
       autofocus: autofocus,
       tristate: tristate,
+      shape: checkboxShape,
       side: side,
     );
     Widget? leading, trailing;

packages/flutter/test/material/checkbox_list_tile_test.dart

@@ -321,8 +321,8 @@ void main() {
     expect(textColor('title'), activeColor);
   });
 
-  testWidgets('CheckboxListTile respects checkbox side', (WidgetTester tester) async {
-    Widget buildApp(BorderSide side) {
+  testWidgets('CheckboxListTile respects checkbox shape and side', (WidgetTester tester) async {
+    Widget buildApp(BorderSide side, OutlinedBorder shape) {
       return MaterialApp(
         home: Material(
           child: Center(
@@ -331,32 +331,47 @@ void main() {
                 value: false,
                 onChanged: (bool? newValue) {},
                 side: side,
+                checkboxShape: shape,
               );
             }),
           ),
         ),
       );
     }
+    const RoundedRectangleBorder border1 = RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(5)));
     const BorderSide side1 = BorderSide(
       color: Color(0xfff44336),
     );
-    await tester.pumpWidget(buildApp(side1));
+    await tester.pumpWidget(buildApp(side1, border1));
     expect(tester.widget<CheckboxListTile>(find.byType(CheckboxListTile)).side, side1);
+    expect(tester.widget<CheckboxListTile>(find.byType(CheckboxListTile)).checkboxShape, border1);
     expect(tester.widget<Checkbox>(find.byType(Checkbox)).side, side1);
+    expect(tester.widget<Checkbox>(find.byType(Checkbox)).shape, border1);
     expect(
       Material.of(tester.element(find.byType(Checkbox))),
       paints
-      ..drrect(color: const Color(0xfff44336)),
+        ..drrect(
+          color: const Color(0xfff44336),
+          outer: RRect.fromLTRBR(11.0, 11.0, 29.0, 29.0, const Radius.circular(5)),
+          inner: RRect.fromLTRBR(12.0, 12.0, 28.0, 28.0, const Radius.circular(4)),
+        ),
     );
+    const RoundedRectangleBorder border2 = RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(5)));
     const BorderSide side2 = BorderSide(
+      width: 4.0,
       color: Color(0xff424242),
     );
-    await tester.pumpWidget(buildApp(side2));
+    await tester.pumpWidget(buildApp(side2, border2));
     expect(tester.widget<Checkbox>(find.byType(Checkbox)).side, side2);
+    expect(tester.widget<Checkbox>(find.byType(Checkbox)).shape, border2);
     expect(
       Material.of(tester.element(find.byType(Checkbox))),
       paints
-      ..drrect(color: const Color(0xff424242)),
+        ..drrect(
+          color: const Color(0xff424242),
+          outer: RRect.fromLTRBR(11.0, 11.0, 29.0, 29.0, const Radius.circular(5)),
+          inner: RRect.fromLTRBR(15.0, 15.0, 25.0, 25.0, const Radius.circular(1)),
+        ),
     );
   });