message: protobuf: s/Protobuf::Empty/ProtobufWkt::Empty/.
  Needed for Google import, WKTs should be referenced in this namespace.
diff: @@ -34,7 +34,7 @@ public:
  }
  ProtobufTypes::MessagePtr createEmptyConfigProto() override {
  - return ProtobufTypes::MessagePtr{new Envoy::Protobuf::Empty()};
  + return ProtobufTypes::MessagePtr{new Envoy::ProtobufWkt::Empty()};
  }
  };
  