Fix all strong mode warnings in protoc-plugin

test/message_generator_test.dart

 #!/usr/bin/env dart
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library message_generator_test;
 
 import 'package:protoc_plugin/indenting_writer.dart';
 import 'package:protoc_plugin/protoc.dart';
 import 'package:protoc_plugin/src/descriptor.pb.dart';
@@ skipping 10 matching lines @@
   static const PhoneNumber_PhoneType WORK = const PhoneNumber_PhoneType._(2, 'WORK');
 
   static const PhoneNumber_PhoneType BUSINESS = WORK;
 
   static const List<PhoneNumber_PhoneType> values = const <PhoneNumber_PhoneType> [
     MOBILE,
     HOME,
     WORK,
   ];
 
-  static final Map<int, PhoneNumber_PhoneType> _byValue = ProtobufEnum.initByValue(values);
-  static PhoneNumber_PhoneType valueOf(int value) => _byValue[value];
+  static final Map<int, dynamic> _byValue = ProtobufEnum.initByValue(values);
+  static PhoneNumber_PhoneType valueOf(int value) => _byValue[value] as PhoneNumber_PhoneType;
   static void $checkItem(PhoneNumber_PhoneType v) {
     if (v is !PhoneNumber_PhoneType) checkItemFailed(v, 'PhoneNumber_PhoneType');
   }
 
   const PhoneNumber_PhoneType._(int v, String n) : super(v, n);
 }
 
 class PhoneNumber extends GeneratedMessage {
   static final BuilderInfo _i = new BuilderInfo('PhoneNumber')
     ..a(1, 'number', PbFieldType.QS)
@@ skipping 10 matching lines @@
   static PbList<PhoneNumber> createRepeated() => new PbList<PhoneNumber>();
   static PhoneNumber getDefault() {
     if (_defaultInstance == null) _defaultInstance = new _ReadonlyPhoneNumber();
     return _defaultInstance;
   }
   static PhoneNumber _defaultInstance;
   static void $checkItem(PhoneNumber v) {
     if (v is !PhoneNumber) checkItemFailed(v, 'PhoneNumber');
   }
 
-  String get number => $_get(0, 1, '');
+  String get number => $_get(0, 1, '') as String;
   void set number(String v) { $_setString(0, 1, v); }
   bool hasNumber() => $_has(0, 1);
   void clearNumber() => clearField(1);
 
-  PhoneNumber_PhoneType get type => $_get(1, 2, null);
+  PhoneNumber_PhoneType get type => $_get(1, 2, null) as PhoneNumber_PhoneType;
   void set type(PhoneNumber_PhoneType v) { setField(2, v); }
   bool hasType() => $_has(1, 2);
   void clearType() => clearField(2);
 
-  String get name => $_get(2, 3, '\$');
+  String get name => $_get(2, 3, '\$') as String;
   void set name(String v) { $_setString(2, 3, v); }
   bool hasName() => $_has(2, 3);
   void clearName() => clearField(3);
 }
 
 class _ReadonlyPhoneNumber extends PhoneNumber with ReadonlyMessageMixin {}
 
 ''';
     FileDescriptorProto fd = new FileDescriptorProto();
     EnumDescriptorProto ed = new EnumDescriptorProto()
-        ..name = 'PhoneType'
-        ..value.addAll([
-            new EnumValueDescriptorProto()
-                ..name = 'MOBILE'
-                ..number = 0,
-            new EnumValueDescriptorProto()
-                ..name = 'HOME'
-                ..number = 1,
-            new EnumValueDescriptorProto()
-                ..name = 'WORK'
-                ..number = 2,
-            new EnumValueDescriptorProto()
-                ..name = 'BUSINESS'
-                ..number = 2]);
+      ..name = 'PhoneType'
+      ..value.addAll([
+        new EnumValueDescriptorProto()
+          ..name = 'MOBILE'
+          ..number = 0,
+        new EnumValueDescriptorProto()
+          ..name = 'HOME'
+          ..number = 1,
+        new EnumValueDescriptorProto()
+          ..name = 'WORK'
+          ..number = 2,
+        new EnumValueDescriptorProto()
+          ..name = 'BUSINESS'
+          ..number = 2
+      ]);
     DescriptorProto md = new DescriptorProto()
-        ..name = 'PhoneNumber'
-        ..field.addAll([
-            // optional PhoneType type = 2 [default = HOME];
-            new FieldDescriptorProto()
-                ..name = 'type'
-                ..number = 2
-                ..label = FieldDescriptorProto_Label.LABEL_OPTIONAL
-                ..type = FieldDescriptorProto_Type.TYPE_ENUM
-                ..typeName = '.PhoneNumber.PhoneType',
-            // required string number = 1;
-            new FieldDescriptorProto()
-                ..name = 'number'
-                ..number = 1
-                ..label = FieldDescriptorProto_Label.LABEL_REQUIRED
-                ..type = FieldDescriptorProto_Type.TYPE_STRING,
-            new FieldDescriptorProto()
-                ..name = 'name'
-                ..number = 3
-                ..label = FieldDescriptorProto_Label.LABEL_OPTIONAL
-                ..type = FieldDescriptorProto_Type.TYPE_STRING
-                ..defaultValue = r'$'
-            ])
-        ..enumType.add(ed);
+      ..name = 'PhoneNumber'
+      ..field.addAll([
+        // optional PhoneType type = 2 [default = HOME];
+        new FieldDescriptorProto()
+          ..name = 'type'
+          ..number = 2
+          ..label = FieldDescriptorProto_Label.LABEL_OPTIONAL
+          ..type = FieldDescriptorProto_Type.TYPE_ENUM
+          ..typeName = '.PhoneNumber.PhoneType',
+        // required string number = 1;
+        new FieldDescriptorProto()
+          ..name = 'number'
+          ..number = 1
+          ..label = FieldDescriptorProto_Label.LABEL_REQUIRED
+          ..type = FieldDescriptorProto_Type.TYPE_STRING,
+        new FieldDescriptorProto()
+          ..name = 'name'
+          ..number = 3
+          ..label = FieldDescriptorProto_Label.LABEL_OPTIONAL
+          ..type = FieldDescriptorProto_Type.TYPE_STRING
+          ..defaultValue = r'$'
+      ])
+      ..enumType.add(ed);
     var options = parseGenerationOptions(
         new CodeGeneratorRequest(), new CodeGeneratorResponse());
 
     FileGenerator fg = new FileGenerator(fd);
     MessageGenerator mg = new MessageGenerator(md, fg, null);
 
     var ctx = new GenerationContext(options);
     mg.register(ctx);
     mg.resolve(ctx);
 
     var writer = new IndentingWriter();
     mg.generate(writer);
     expect(writer.toString(), expected);
   });
 }