Protobuf: Ruby JSON serialization is incompatible when using well known types

[yonekawa]

Ruby JSON serialization seems to be incompatible when using Well-Known types.

For example, I'm using google.protobuf.Timestamp.
It expects to be mapped RFC3339 string. However, ruby binding encodes it to be object.

Google::Protobuf::Timestamp.new(seconds: Time.current.to_i, nanos: Time.current.nsec).to_json
=> "{\"seconds\":1524627489,\"nanos\":820635000}"

failure case code

sample.proto

syntax = "proto3";
package proto.foo;
import "google/protobuf/timestamp.proto";

@option java_outer_classname = "Protobuf";

message Record {
  google.protobuf.Timestamp created_at = 1;
  google.protobuf.Timestamp updated_at = 2;
}

serialize.rb

Proto::Foo::Record.new(
  created_at: Google::Protobuf::Timestamp(seconds: created_at.to_i, nanos: created_at.nsec),
  updated_at: Google::Protobuf::Timestamp(seconds: updated_at.to_i, nanos: updated_at.nsec)
).to_json

parse.java

Protobuf.Record.Builder builder = Protobuf.Record.newBuilder();
JsonFormat.parser().merge(json, builder);
// => com.google.protobuf.InvalidProtocolBufferException

[TeBoring]

ruby hasn't passed conformance test yet. This will be fixed.

[TeBoring]

Most of well known type issue in json have been fixed.
There are still some edge cases broken. See conformance/failure_list_ruby.txt for details.