Merge pull request #290 from juliuscanute/stable-null-safety

stable version of null-safety

.github/workflows/dart.yml

@@ -8,18 +8,16 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-java@v1
-      with:
-        java-version: '12.x'
-    - uses: subosito/flutter-action@v1
-      with:
-        channel: 'stable'
-    - name: Version
-      run: flutter doctor -v
-    - name: Install dependencies
-      run: flutter pub get
-    - name: Format
-      run: dartfmt -n --set-exit-if-changed .
-    - name: Linter
-      run: dartanalyzer . --options=analysis_options.yaml --fatal-hints
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: '12.x'
+      - uses: subosito/flutter-action@v1
+      - name: Version
+        run: flutter doctor -v
+      - name: Install dependencies
+        run: flutter pub get
+      - name: Format
+        run: flutter format -n --set-exit-if-changed .
+      - name: Linter
+        run: flutter analyze

analysis_options.yaml

@@ -1,107 +1 @@
-include: package:pedantic/analysis_options.yaml
-
-linter:
-  rules:
-    - always_put_required_named_parameters_first
-    - always_require_non_null_named_parameters
-    - avoid_annotating_with_dynamic
-    - avoid_bool_literals_in_conditional_expressions
-    - avoid_catching_errors
-    - avoid_classes_with_only_static_members
-    - avoid_empty_else
-    - avoid_init_to_null
-    - avoid_null_checks_in_equality_operators
-    - avoid_print
-    - avoid_relative_lib_imports
-    - avoid_return_types_on_setters
-    - avoid_returning_null
-    - avoid_returning_null_for_future
-    - avoid_returning_null_for_void
-    - avoid_shadowing_type_parameters
-    - avoid_single_cascade_in_expression_statements
-    - avoid_types_as_parameter_names
-    - avoid_types_on_closure_parameters
-    - avoid_void_async
-    - await_only_futures
-    - camel_case_types
-    - cancel_subscriptions
-    - cascade_invocations
-    - close_sinks
-    - comment_references
-    - constant_identifier_names
-    - control_flow_in_finally
-    - curly_braces_in_flow_control_structures
-    - directives_ordering
-    - empty_catches
-    - empty_constructor_bodies
-    - empty_statements
-    - file_names
-    - hash_and_equals
-    - implementation_imports
-    - invariant_booleans
-    - iterable_contains_unrelated_type
-    - join_return_with_assignment
-    - library_names
-    - library_prefixes
-    - list_remove_unrelated_type
-    - no_duplicate_case_values
-    - non_constant_identifier_names
-    - null_closures
-    - only_throw_errors
-    - overridden_fields
-    - package_api_docs
-    - package_names
-    - package_prefixed_library_names
-    - prefer_collection_literals
-    - prefer_conditional_assignment
-    - prefer_const_declarations
-    - prefer_contains
-    - prefer_equal_for_default_values
-    - prefer_final_fields
-    - prefer_for_elements_to_map_fromIterable
-    - prefer_foreach
-    - prefer_function_declarations_over_variables
-    - prefer_if_elements_to_conditional_expressions
-    - prefer_if_null_operators
-    - prefer_initializing_formals
-    - prefer_inlined_adds
-    - prefer_int_literals
-    - prefer_interpolation_to_compose_strings
-    - prefer_is_empty
-    - prefer_is_not_empty
-    - prefer_iterable_whereType
-    - prefer_null_aware_operators
-    - prefer_void_to_null
-    - provide_deprecation_message
-    - recursive_getters
-    - slash_for_doc_comments
-    - sort_child_properties_last
-    - sort_constructors_first
-    - sort_pub_dependencies
-    - sort_unnamed_constructors_first
-    - test_types_in_equals
-    - throw_in_finally
-    - type_init_formals
-    - unawaited_futures
-    - unnecessary_await_in_return
-    - unnecessary_brace_in_string_interps
-    - unnecessary_const
-    - unnecessary_getters_setters
-    - unnecessary_lambdas
-    - unnecessary_new
-    - unnecessary_null_aware_assignments
-    - unnecessary_null_in_if_null_operators
-    - unnecessary_overrides
-    - unnecessary_parenthesis
-    - unnecessary_statements
-    - unnecessary_this
-    - unrelated_type_equality_checks
-    - unsafe_html
-    - use_full_hex_values_for_flutter_colors
-    - use_function_type_syntax_for_parameters
-    - use_rethrow_when_possible
-    - use_setters_to_change_properties
-    - use_string_buffers
-    - use_to_and_as_if_applicable
-    - valid_regexps
-    - void_checks
+include: package:pedantic/analysis_options.yaml

example/lib/main.dart

@@ -7,17 +7,13 @@ import 'package:qr_code_scanner/qr_code_scanner.dart';
 void main() => runApp(MaterialApp(home: QRViewExample()));
 
 class QRViewExample extends StatefulWidget {
-  const QRViewExample({
-    Key key,
-  }) : super(key: key);
-
   @override
   State<StatefulWidget> createState() => _QRViewExampleState();
 }
 
 class _QRViewExampleState extends State<QRViewExample> {
-  Barcode result;
-  QRViewController controller;
+  Barcode? result;
+  QRViewController? controller;
   final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
 
   // In order to get hot reload to work we need to pause the camera if the platform
@@ -26,9 +22,9 @@ class _QRViewExampleState extends State<QRViewExample> {
   void reassemble() {
     super.reassemble();
     if (Platform.isAndroid) {
-      controller.pauseCamera();
+      controller!.pauseCamera();
     }
-    controller.resumeCamera();
+    controller!.resumeCamera();
   }
 
   @override
@@ -46,7 +42,7 @@ class _QRViewExampleState extends State<QRViewExample> {
                 children: <Widget>[
                   if (result != null)
                     Text(
-                        'Barcode Type: ${describeEnum(result.format)}   Data: ${result.code}')
+                        'Barcode Type: ${describeEnum(result!.format)}   Data: ${result!.code}')
                   else
                     Text('Scan a code'),
                   Row(
@@ -79,7 +75,7 @@ class _QRViewExampleState extends State<QRViewExample> {
                               builder: (context, snapshot) {
                                 if (snapshot.data != null) {
                                   return Text(
-                                      'Camera facing ${describeEnum(snapshot.data)}');
+                                      'Camera facing ${describeEnum(snapshot.data!)}');
                                 } else {
                                   return Text('loading');
                                 }

example/pubspec.yaml

@@ -3,17 +3,14 @@ description: Demonstrates how to use the flutter_qr plugin.
 publish_to: 'none'
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter:
     sdk: flutter
 
-  # The following adds the Cupertino Icons font to your application.
-  # Use with the CupertinoIcons class for iOS style icons.
-  cupertino_icons: ^0.1.2
-
 dev_dependencies:
+  pedantic: ^1.11.0
   flutter_test:
     sdk: flutter
 

lib/src/lifecycle_event_handler.dart

@@ -3,28 +3,20 @@ import 'package:flutter/foundation.dart';
 
 class LifecycleEventHandler extends WidgetsBindingObserver {
   LifecycleEventHandler({
-    this.resumeCallBack,
-    this.suspendingCallBack,
+    required this.resumeCallBack,
   });
 
-  final AsyncCallback resumeCallBack;
-  final AsyncCallback suspendingCallBack;
+  late final AsyncCallback resumeCallBack;
 
   @override
   Future<void> didChangeAppLifecycleState(AppLifecycleState state) async {
     switch (state) {
       case AppLifecycleState.resumed:
-        if (resumeCallBack != null) {
-          await resumeCallBack();
-        }
+        await resumeCallBack();
         break;
       case AppLifecycleState.inactive:
       case AppLifecycleState.paused:
       case AppLifecycleState.detached:
-        if (suspendingCallBack != null) {
-          await suspendingCallBack();
-        }
-        break;
     }
   }
 }

lib/src/qr_code_scanner.dart

@@ -20,23 +20,21 @@ typedef PermissionSetCallback = void Function(QRViewController, bool);
 /// and the barcode scanner gets displayed.
 class QRView extends StatefulWidget {
   const QRView({
-    @required Key key,
-    @required this.onQRViewCreated,
+    required Key key,
+    required this.onQRViewCreated,
     this.overlay,
     this.overlayMargin = EdgeInsets.zero,
     this.cameraFacing = CameraFacing.back,
     this.onPermissionSet,
-    this.formatsAllowed,
-  })  : assert(key != null),
-        assert(onQRViewCreated != null),
-        super(key: key);
+    this.formatsAllowed = const <BarcodeFormat>[],
+  }) : super(key: key);
 
   /// [onQRViewCreated] gets called when the view is created
   final QRViewCreatedCallback onQRViewCreated;
 
   /// Use [overlay] to provide an overlay for the view.
   /// This can be used to create a certain scan area.
-  final QrScannerOverlayShape overlay;
+  final QrScannerOverlayShape? overlay;
 
   /// Use [overlayMargin] to provide a margin to [overlay]
   final EdgeInsetsGeometry overlayMargin;
@@ -48,7 +46,7 @@ class QRView extends StatefulWidget {
   final CameraFacing cameraFacing;
 
   /// Calls the provided [onPermissionSet] callback when the permission is set.
-  final PermissionSetCallback onPermissionSet;
+  final PermissionSetCallback? onPermissionSet;
 
   /// Use [formatsAllowed] to specify which formats needs to be scanned.
   final List<BarcodeFormat> formatsAllowed;
@@ -58,21 +56,14 @@ class QRView extends StatefulWidget {
 }
 
 class _QRViewState extends State<QRView> {
-  var _channel;
-  var _observer;
+  late MethodChannel _channel;
+  late LifecycleEventHandler _observer;
 
   @override
   void initState() {
     super.initState();
-    _observer = LifecycleEventHandler(
-        resumeCallBack: () async => {
-              if (_channel != null)
-                {
-                  QRViewController.updateDimensions(widget.key, _channel,
-                      overlay: widget.overlay)
-                }
-            });
-    WidgetsBinding.instance.addObserver(_observer);
+    _observer = LifecycleEventHandler(resumeCallBack: updateDimensions);
+    WidgetsBinding.instance!.addObserver(_observer);
   }
 
   @override
@@ -90,15 +81,17 @@ class _QRViewState extends State<QRView> {
   @override
   void dispose() {
     super.dispose();
-    WidgetsBinding.instance.removeObserver(_observer);
+    WidgetsBinding.instance!.removeObserver(_observer);
   }
 
-  bool onNotification(notification) {
-    Future.microtask(() => {
-          QRViewController.updateDimensions(widget.key, _channel,
-              overlay: widget.overlay)
-        });
+  Future<void> updateDimensions() async {
+    await QRViewController.updateDimensions(
+        widget.key as GlobalKey<State<StatefulWidget>>, _channel,
+        overlay: widget.overlay);
+  }
 
+  bool onNotification(notification) {
+    updateDimensions();
     return false;
   }
 
@@ -109,7 +102,7 @@ class _QRViewState extends State<QRView> {
         Container(
           padding: widget.overlayMargin,
           decoration: ShapeDecoration(
-            shape: widget.overlay,
+            shape: widget.overlay!,
           ),
         )
       ],
@@ -139,7 +132,7 @@ class _QRViewState extends State<QRView> {
         break;
       default:
         throw UnsupportedError(
-            "Trying to use the default webview implementation for $defaultTargetPlatform but there isn't a default one");
+            "Trying to use the default qrview implementation for $defaultTargetPlatform but there isn't a default one");
     }
     return _platformQrView;
   }
@@ -149,19 +142,21 @@ class _QRViewState extends State<QRView> {
 
     // Start scan after creation of the view
     final controller = QRViewController._(
-        _channel, widget.key, widget.onPermissionSet, widget.cameraFacing)
-      .._startScan(widget.key, widget.overlay, widget.formatsAllowed);
+        _channel,
+        widget.key as GlobalKey<State<StatefulWidget>>?,
+        widget.onPermissionSet,
+        widget.cameraFacing)
+      .._startScan(widget.key as GlobalKey<State<StatefulWidget>>,
+          widget.overlay, widget.formatsAllowed);
 
     // Initialize the controller for controlling the QRView
-    if (widget.onQRViewCreated != null) {
-      widget.onQRViewCreated(controller);
-    }
+    widget.onQRViewCreated(controller);
   }
 }
 
 class _QrCameraSettings {
   _QrCameraSettings({
-    this.cameraFacing,
+    this.cameraFacing = CameraFacing.unknown,
   });
 
   final CameraFacing cameraFacing;
@@ -174,8 +169,8 @@ class _QrCameraSettings {
 }
 
 class QRViewController {
-  QRViewController._(MethodChannel channel, GlobalKey qrKey,
-      PermissionSetCallback onPermissionSet, CameraFacing cameraFacing)
+  QRViewController._(MethodChannel channel, GlobalKey? qrKey,
+      PermissionSetCallback? onPermissionSet, CameraFacing cameraFacing)
       : _channel = channel,
         _cameraFacing = cameraFacing {
     _channel.setMethodCallHandler((call) async {
@@ -186,9 +181,9 @@ class QRViewController {
             final code = args['code'] as String;
             final rawType = args['type'] as String;
             // Raw bytes are only supported by Android.
-            final rawBytes = args['rawBytes'] as List<int>;
+            final rawBytes = args['rawBytes'] as List<int>?;
             final format = BarcodeTypesExtension.fromString(rawType);
-            if (format != null) {
+            if (format != BarcodeFormat.unknown) {
               final barcode = Barcode(code, format, rawBytes);
               _scanUpdateController.sink.add(barcode);
             } else {
@@ -197,15 +192,14 @@ class QRViewController {
           }
           break;
         case 'onPermissionSet':
-          await getSystemFeatures(); // if we have no permission all features will not be avaible
-          if (call.arguments != null) {
-            if (call.arguments as bool) {
+          if (call.arguments != null && call.arguments is bool) {
+            if (call.arguments) {
               _hasPermissions = true;
             } else {
               _hasPermissions = false;
             }
             if (onPermissionSet != null) {
-              onPermissionSet(this, call.arguments as bool);
+              onPermissionSet(this, call.arguments);
             }
           }
           break;
@@ -220,20 +214,17 @@ class QRViewController {
 
   Stream<Barcode> get scannedDataStream => _scanUpdateController.stream;
 
-  SystemFeatures _features;
-  bool _hasPermissions;
-
-  SystemFeatures get systemFeatures => _features;
+  bool _hasPermissions = false;
   bool get hasPermissions => _hasPermissions;
 
   /// Starts the barcode scanner
-  Future<void> _startScan(GlobalKey key, QrScannerOverlayShape overlay,
-      List<BarcodeFormat> barcodeFormats) async {
+  Future<void> _startScan(GlobalKey key, QrScannerOverlayShape? overlay,
+      List<BarcodeFormat>? barcodeFormats) async {
     // We need to update the dimension before the scan is started.
     try {
       await QRViewController.updateDimensions(key, _channel, overlay: overlay);
       return await _channel.invokeMethod(
-          'startScan', barcodeFormats?.map((e) => e.asInt())?.toList() ?? []);
+          'startScan', barcodeFormats?.map((e) => e.asInt()).toList() ?? []);
     } on PlatformException catch (e) {
       throw CameraException(e.code, e.message);
     }
@@ -262,7 +253,7 @@ class QRViewController {
   }
 
   /// Get flashlight status
-  Future<bool> getFlashStatus() async {
+  Future<bool?> getFlashStatus() async {
     try {
       return await _channel.invokeMethod('getFlashInfo');
     } on PlatformException catch (e) {
@@ -273,7 +264,7 @@ class QRViewController {
   /// Toggles the flashlight between available modes
   Future<void> toggleFlash() async {
     try {
-      await _channel.invokeMethod('toggleFlash') as bool;
+      await _channel.invokeMethod('toggleFlash') as bool?;
     } on PlatformException catch (e) {
       throw CameraException(e.code, e.message);
     }
@@ -311,7 +302,10 @@ class QRViewController {
     try {
       var features =
           await _channel.invokeMapMethod<String, dynamic>('getSystemFeatures');
-      return SystemFeatures.fromJson(features);
+      if (features != null) {
+        return SystemFeatures.fromJson(features);
+      }
+      throw CameraException('Error', 'Could not get system features');
     } on PlatformException catch (e) {
       throw CameraException(e.code, e.message);
     }
@@ -324,12 +318,13 @@ class QRViewController {
   }
 
   /// Updates the view dimensions for iOS.
-  static Future<void> updateDimensions(GlobalKey key, MethodChannel channel,
-      {QrScannerOverlayShape overlay}) async {
+  static Future<bool> updateDimensions(GlobalKey key, MethodChannel channel,
+      {QrScannerOverlayShape? overlay}) async {
     if (defaultTargetPlatform == TargetPlatform.iOS) {
-      // Add small delay to ensure the renderbox is loaded
+      // Add small delay to ensure the render box is loaded
       await Future.delayed(Duration(milliseconds: 100));
-      final RenderBox renderBox = key.currentContext.findRenderObject();
+      if (key.currentContext == null) return false;
+      final renderBox = key.currentContext!.findRenderObject() as RenderBox;
       try {
         await channel.invokeMethod('setDimensions', {
           'width': renderBox.size.width,
@@ -337,9 +332,11 @@ class QRViewController {
           'scanArea': overlay?.cutOutSize ?? 0,
           'scanAreaOffset': overlay?.cutOutBottomOffset ?? 0
         });
+        return true;
       } on PlatformException catch (e) {
         throw CameraException(e.code, e.message);
       }
     }
+    return false;
   }
 }

lib/src/qr_scanner_overlay_shape.dart

@@ -11,10 +11,7 @@ class QrScannerOverlayShape extends ShapeBorder {
     this.borderLength = 40,
     this.cutOutSize = 250,
     this.cutOutBottomOffset = 0,
-  }) : assert(
-            cutOutSize != null ??
-                cutOutSize != null ??
-                borderLength <= cutOutSize / 2 + borderWidth * 2,
+  }) : assert(borderLength <= cutOutSize / 2 + borderWidth * 2,
             "Border can't be larger than ${cutOutSize / 2 + borderWidth * 2}");
 
   final Color borderColor;
@@ -29,14 +26,14 @@ class QrScannerOverlayShape extends ShapeBorder {
   EdgeInsetsGeometry get dimensions => const EdgeInsets.all(10);
 
   @override
-  Path getInnerPath(Rect rect, {TextDirection textDirection}) {
+  Path getInnerPath(Rect rect, {TextDirection? textDirection}) {
     return Path()
       ..fillType = PathFillType.evenOdd
       ..addPath(getOuterPath(rect), Offset.zero);
   }
 
   @override
-  Path getOuterPath(Rect rect, {TextDirection textDirection}) {
+  Path getOuterPath(Rect rect, {TextDirection? textDirection}) {
     Path _getLeftTopPath(Rect rect) {
       return Path()
         ..moveTo(rect.left, rect.bottom)
@@ -60,7 +57,7 @@ class QrScannerOverlayShape extends ShapeBorder {
   }
 
   @override
-  void paint(Canvas canvas, Rect rect, {TextDirection textDirection}) {
+  void paint(Canvas canvas, Rect rect, {TextDirection? textDirection}) {
     final width = rect.width;
     final borderWidthSize = width / 2;
     final height = rect.height;
@@ -68,9 +65,7 @@ class QrScannerOverlayShape extends ShapeBorder {
     final _borderLength = borderLength > cutOutSize / 2 + borderWidth * 2
         ? borderWidthSize / 2
         : borderLength;
-    final _cutOutSize = cutOutSize != null && cutOutSize < width
-        ? cutOutSize
-        : width - borderOffset;
+    final _cutOutSize = cutOutSize < width ? cutOutSize : width - borderOffset;
 
     final backgroundPaint = Paint()
       ..color = overlayColor

lib/src/types/barcode.dart

@@ -12,5 +12,5 @@ class Barcode {
   final BarcodeFormat format;
 
   /// Raw bytes are only supported by Android.
-  final List<int> rawBytes;
+  final List<int>? rawBytes;
 }

lib/src/types/barcode_format.dart

@@ -53,7 +53,10 @@ enum BarcodeFormat {
   upcE,
 
   /// UPC/EAN extension format. Not a stand-alone format.
-  upcEanExtension
+  upcEanExtension,
+
+  /// Unknown
+  unknown
 }
 
 extension BarcodeTypesExtension on BarcodeFormat {
@@ -65,57 +68,40 @@ extension BarcodeTypesExtension on BarcodeFormat {
     switch (format) {
       case 'AZTEC':
         return BarcodeFormat.aztec;
-        break;
       case 'CODABAR':
         return BarcodeFormat.codabar;
-        break;
       case 'CODE_39':
         return BarcodeFormat.code39;
-        break;
       case 'CODE_93':
         return BarcodeFormat.code93;
-        break;
       case 'CODE_128':
         return BarcodeFormat.code128;
-        break;
       case 'DATA_MATRIX':
         return BarcodeFormat.dataMatrix;
-        break;
       case 'EAN_8':
         return BarcodeFormat.ean8;
-        break;
       case 'EAN_13':
         return BarcodeFormat.ean13;
-        break;
       case 'ITF':
         return BarcodeFormat.itf;
-        break;
       case 'MAXICODE':
         return BarcodeFormat.maxicode;
-        break;
       case 'PDF_417':
         return BarcodeFormat.pdf417;
-        break;
       case 'QR_CODE':
         return BarcodeFormat.qrcode;
-        break;
       case 'RSS14':
         return BarcodeFormat.rss14;
-        break;
       case 'RSS_EXPANDED':
         return BarcodeFormat.rssExpanded;
-        break;
       case 'UPC_A':
         return BarcodeFormat.upcA;
-        break;
       case 'UPC_E':
         return BarcodeFormat.upcE;
-        break;
       case 'UPC_EAN_EXTENSION':
         return BarcodeFormat.upcEanExtension;
-        break;
       default:
-        return null;
+        return BarcodeFormat.unknown;
     }
   }
 
@@ -123,57 +109,40 @@ extension BarcodeTypesExtension on BarcodeFormat {
     switch (this) {
       case BarcodeFormat.aztec:
         return 'AZTEC';
-        break;
       case BarcodeFormat.codabar:
         return 'CODABAR';
-        break;
       case BarcodeFormat.code39:
         return 'CODE_39';
-        break;
       case BarcodeFormat.code93:
         return 'CODE_93';
-        break;
       case BarcodeFormat.code128:
         return 'CODE_128';
-        break;
       case BarcodeFormat.dataMatrix:
         return 'DATA_MATRIX';
-        break;
       case BarcodeFormat.ean8:
         return 'EAN_8';
-        break;
       case BarcodeFormat.ean13:
         return 'EAN_13';
-        break;
       case BarcodeFormat.itf:
         return 'ITF';
-        break;
       case BarcodeFormat.maxicode:
         return 'MAXICODE';
-        break;
       case BarcodeFormat.pdf417:
         return 'PDF_417';
-        break;
       case BarcodeFormat.qrcode:
         return 'QR_CODE';
-        break;
       case BarcodeFormat.rss14:
         return 'RSS14';
-        break;
       case BarcodeFormat.rssExpanded:
         return 'RSS_EXPANDED';
-        break;
       case BarcodeFormat.upcA:
         return 'UPC_A';
-        break;
       case BarcodeFormat.upcE:
         return 'UPC_E';
-        break;
       case BarcodeFormat.upcEanExtension:
         return 'UPC_EAN_EXTENSION';
-        break;
       default:
-        return 'NOT_VALID';
+        return 'UNKNOWN';
     }
   }
 }

lib/src/types/camera.dart

@@ -3,5 +3,8 @@ enum CameraFacing {
   back,
 
   /// Shows front facing camera.
-  front
+  front,
+
+  /// Unknown camera
+  unknown
 }

lib/src/types/camera_exception.dart

@@ -7,7 +7,7 @@ class CameraException implements Exception {
   String code;
 
   /// Textual description of the error.
-  String description;
+  String? description;
 
   @override
   String toString() => 'CameraException($code, $description)';

pubspec.yaml

@@ -5,7 +5,7 @@ homepage: https://juliuscanute.com
 repository: https://github.com/juliuscanute/qr_code_scanner
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
   flutter: ">=1.10.0"
 
 dependencies:
@@ -13,7 +13,7 @@ dependencies:
     sdk: flutter
 
 dev_dependencies:
-  pedantic: ^1.9.2
+  pedantic: ^1.11.0
 
 flutter:
   plugin: