Fix google protobuf WellKnownTypes: Empty, Duration and Timestamp (#1231)

* Fix google protobuf WellKnownTypes: Timestamp and Duration

* Fix protobuf Empty

* .

* small refactor

* 006

* fix

* policy

* ---

* <PackageReference Include="ProtoBufJsonConverter" Version="0.7.0" />

test/WireMock.Net.Tests/Grpc/greet.proto

@@ -1,33 +1,41 @@
-// Copyright 2019 The gRPC Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 syntax = "proto3";
 
 package greet;
 
-// The greeting service definition.
+import "google/protobuf/empty.proto";
+import "google/protobuf/timestamp.proto";
+import "google/protobuf/duration.proto";
+
 service Greeter {
-  // Sends a greeting
+  rpc SayNothing (google.protobuf.Empty) returns (google.protobuf.Empty);
   rpc SayHello (HelloRequest) returns (HelloReply);
+  rpc SayEmpty (MyMessageEmpty) returns (MyMessageEmpty);
+  rpc SayTimestamp (MyMessageTimestamp) returns (MyMessageTimestamp);
+  rpc SayDuration (MyMessageDuration) returns (MyMessageDuration);
 }
 
-// The request message containing the user's name.
 message HelloRequest {
   string name = 1;
 }
 
-// The response message containing the greetings
 message HelloReply {
   string message = 1;
+  enum PhoneType {
+    none = 0;
+    mobile = 1;
+    home = 2;
+  }
+  PhoneType phoneType = 2;
+}
+
+message MyMessageTimestamp {
+    google.protobuf.Timestamp ts = 1;
+}
+
+message MyMessageDuration {
+    google.protobuf.Duration du = 1;
+}
+
+message MyMessageEmpty {
+    google.protobuf.Empty e = 1;
 }