feat: migrate windows/application_package.dart to null-safety (#88081)

packages/flutter_tools/lib/src/windows/application_package.dart

@@ -2,10 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
-import 'package:meta/meta.dart';
-
 import '../application_package.dart';
 import '../base/file_system.dart';
 import '../base/utils.dart';
@@ -15,7 +11,7 @@ import '../cmake_project.dart';
 import '../globals_null_migrated.dart' as globals;
 
 abstract class WindowsApp extends ApplicationPackage {
-  WindowsApp({@required String projectBundleId}) : super(id: projectBundleId);
+  WindowsApp({required String projectBundleId}) : super(id: projectBundleId);
 
   /// Creates a new [WindowsApp] from a windows sub project.
   factory WindowsApp.fromWindowsProject(WindowsProject project) {
@@ -41,7 +37,7 @@ abstract class WindowsApp extends ApplicationPackage {
 
 class PrebuiltWindowsApp extends WindowsApp {
   PrebuiltWindowsApp({
-    @required String executable,
+    required String executable,
   }) : _executable = executable,
        super(projectBundleId: executable);
 
@@ -56,14 +52,14 @@ class PrebuiltWindowsApp extends WindowsApp {
 
 class BuildableWindowsApp extends WindowsApp {
   BuildableWindowsApp({
-    @required this.project,
+    required this.project,
   }) : super(projectBundleId: project.parent.manifest.appName);
 
   final WindowsProject project;
 
   @override
   String executable(BuildMode buildMode) {
-    final String binaryName = getCmakeExecutableName(project);
+    final String? binaryName = getCmakeExecutableName(project);
     return globals.fs.path.join(
         getWindowsBuildDirectory(),
         'runner',
@@ -77,12 +73,12 @@ class BuildableWindowsApp extends WindowsApp {
 }
 
 class BuildableUwpApp extends ApplicationPackage {
-  BuildableUwpApp({@required this.project}) : super(id: project.packageGuid);
+  BuildableUwpApp({required this.project}) : super(id: project.packageGuid ?? 'com.example.placeholder');
 
   final WindowsUwpProject project;
 
-  String get projectVersion => project.packageVersion;
+  String? get projectVersion => project.packageVersion;
 
   @override
-  String get name => getCmakeExecutableName(project);
+  String? get name => getCmakeExecutableName(project);
 }