Make AndroidApk nullable in stopApp. (#113353)

packages/flutter_tools/lib/src/android/android_device.dart

@@ -720,7 +720,7 @@ class AndroidDevice extends Device {
 
   @override
   Future<bool> stopApp(
-    AndroidApk app, {
+    AndroidApk? app, {
     String? userIdentifier,
   }) {
     if (app == null) {

packages/flutter_tools/test/commands.shard/hermetic/daemon_test.dart

@@ -905,7 +905,7 @@ class FakeAndroidDevice extends Fake implements AndroidDevice {
   ApplicationPackage? stopAppPackage;
   @override
   Future<bool> stopApp(
-    ApplicationPackage app, {
+    ApplicationPackage? app, {
     String? userIdentifier,
   }) async {
     stopAppPackage = app;

packages/flutter_tools/test/commands.shard/hermetic/proxied_devices_test.dart

@@ -326,7 +326,7 @@ class FakeAndroidDevice extends Fake implements AndroidDevice {
   ApplicationPackage? stopAppPackage;
   @override
   Future<bool> stopApp(
-    ApplicationPackage app, {
+    ApplicationPackage? app, {
     String? userIdentifier,
   }) async {
     stopAppPackage = app;

packages/flutter_tools/test/general.shard/android/android_device_test.dart

@@ -454,6 +454,13 @@ Uptime: 441088659 Realtime: 521464097
     // contains identifier for platform in memory info.
     expect(json, containsPair('platform', 'Android'));
   });
+
+  testWithoutContext('AndroidDevice stopApp does nothing if app is not passed', () async {
+    final AndroidDevice device = setUpAndroidDevice();
+
+    expect(await device.stopApp(null), isFalse);
+  });
+
 }
 
 AndroidDevice setUpAndroidDevice({