static GsonGrpcJsonMarshallerBuilder builderForGson() {
        return new GsonGrpcJsonMarshallerBuilder();
    }
Returns a new {@link GsonGrpcJsonMarshallerBuilder}. This implementation internally uses
<a href="https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/util/JsonFormat">JsonFormat</a>
and {@code Gson} to serialize and deserialize messages.
Note:
<a href="https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/util/JsonFormat">JsonFormat</a>
has a known <a href="https://github.com/curioswitch/protobuf-jackson#benchmarks">performance issue</a>.
Use this method only when
1) you're using Protobuf 2 or 2) you have an issue with
<a href="https://github.com/curioswitch/protobuf-jackson">protobuf-jackson</a>.
grpc/src/main/java/com/linecorp/armeria/common/grpc/GrpcJsonMarshaller.java