Fix all strong mode warnings in protoc-plugin

lib/src/plugin.pb.dart

Index: lib/src/plugin.pb.dart
diff --git a/lib/src/plugin.pb.dart b/lib/src/plugin.pb.dart
index 9ac0ae40d884a17af2a0e71295289131a55177c7..8a6a34dba51059c4c550ab318eed3de6e87690fc 100644
--- a/lib/src/plugin.pb.dart
+++ b/lib/src/plugin.pb.dart
@@ -8,9 +8,9 @@ import 'descriptor.pb.dart' as proto2;
 
 class CodeGeneratorRequest extends GeneratedMessage {
   static final BuilderInfo _i = new BuilderInfo('CodeGeneratorRequest')
-    ..p(1, 'fileToGenerate', PbFieldType.PS)
-    ..a(2, 'parameter', PbFieldType.OS)
-    ..pp(15, 'protoFile', PbFieldType.PM, proto2.FileDescriptorProto.$checkItem, proto2.FileDescriptorProto.create)
+    ..p/*<String>*/(1, 'fileToGenerate', PbFieldType.PS)
+    ..a/*<String>*/(2, 'parameter', PbFieldType.OS)
+    ..pp/*<proto2.FileDescriptorProto>*/(15, 'protoFile', PbFieldType.PM, proto2.FileDescriptorProto.$checkItem, proto2.FileDescriptorProto.create)
   ;
 
   CodeGeneratorRequest() : super();
@@ -29,23 +29,23 @@ class CodeGeneratorRequest extends GeneratedMessage {
     if (v is !CodeGeneratorRequest) checkItemFailed(v, 'CodeGeneratorRequest');
   }
 
-  List<String> get fileToGenerate => getField(1);
+  List<String> get fileToGenerate => $_get(0, 1, null);
 
-  String get parameter => getField(2);
-  void set parameter(String v) { setField(2, v); }
-  bool hasParameter() => hasField(2);
+  String get parameter => $_get(1, 2, '');
+  void set parameter(String v) { $_setString(1, 2, v); }
+  bool hasParameter() => $_has(1, 2);
   void clearParameter() => clearField(2);
 
-  List<proto2.FileDescriptorProto> get protoFile => getField(15);
+  List<proto2.FileDescriptorProto> get protoFile => $_get(2, 15, null);
 }
 
 class _ReadonlyCodeGeneratorRequest extends CodeGeneratorRequest with ReadonlyMessageMixin {}
 
 class CodeGeneratorResponse_File extends GeneratedMessage {
   static final BuilderInfo _i = new BuilderInfo('CodeGeneratorResponse_File')
-    ..a(1, 'name', PbFieldType.OS)
-    ..a(2, 'insertionPoint', PbFieldType.OS)
-    ..a(15, 'content', PbFieldType.OS)
+    ..a/*<String>*/(1, 'name', PbFieldType.OS)
+    ..a/*<String>*/(2, 'insertionPoint', PbFieldType.OS)
+    ..a/*<String>*/(15, 'content', PbFieldType.OS)
     ..hasRequiredFields = false
   ;
 
@@ -65,19 +65,19 @@ class CodeGeneratorResponse_File extends GeneratedMessage {
     if (v is !CodeGeneratorResponse_File) checkItemFailed(v, 'CodeGeneratorResponse_File');
   }
 
-  String get name => getField(1);
-  void set name(String v) { setField(1, v); }
-  bool hasName() => hasField(1);
+  String get name => $_get(0, 1, '');
+  void set name(String v) { $_setString(0, 1, v); }
+  bool hasName() => $_has(0, 1);
   void clearName() => clearField(1);
 
-  String get insertionPoint => getField(2);
-  void set insertionPoint(String v) { setField(2, v); }
-  bool hasInsertionPoint() => hasField(2);
+  String get insertionPoint => $_get(1, 2, '');
+  void set insertionPoint(String v) { $_setString(1, 2, v); }
+  bool hasInsertionPoint() => $_has(1, 2);
   void clearInsertionPoint() => clearField(2);
 
-  String get content => getField(15);
-  void set content(String v) { setField(15, v); }
-  bool hasContent() => hasField(15);
+  String get content => $_get(2, 15, '');
+  void set content(String v) { $_setString(2, 15, v); }
+  bool hasContent() => $_has(2, 15);
   void clearContent() => clearField(15);
 }
 
@@ -85,8 +85,8 @@ class _ReadonlyCodeGeneratorResponse_File extends CodeGeneratorResponse_File wit
 
 class CodeGeneratorResponse extends GeneratedMessage {
   static final BuilderInfo _i = new BuilderInfo('CodeGeneratorResponse')
-    ..a(1, 'error', PbFieldType.OS)
-    ..pp(15, 'file', PbFieldType.PM, CodeGeneratorResponse_File.$checkItem, CodeGeneratorResponse_File.create)
+    ..a/*<String>*/(1, 'error', PbFieldType.OS)
+    ..pp/*<CodeGeneratorResponse_File>*/(15, 'file', PbFieldType.PM, CodeGeneratorResponse_File.$checkItem, CodeGeneratorResponse_File.create)
     ..hasRequiredFields = false
   ;
 
@@ -106,12 +106,12 @@ class CodeGeneratorResponse extends GeneratedMessage {
     if (v is !CodeGeneratorResponse) checkItemFailed(v, 'CodeGeneratorResponse');
   }
 
-  String get error => getField(1);
-  void set error(String v) { setField(1, v); }
-  bool hasError() => hasField(1);
+  String get error => $_get(0, 1, '');
+  void set error(String v) { $_setString(0, 1, v); }
+  bool hasError() => $_has(0, 1);
   void clearError() => clearField(1);
 
-  List<CodeGeneratorResponse_File> get file => getField(15);
+  List<CodeGeneratorResponse_File> get file => $_get(1, 15, null);
 }
 
 class _ReadonlyCodeGeneratorResponse extends CodeGeneratorResponse with ReadonlyMessageMixin {}