jsonpb: Unmarshal error for Oneof field with Capital First Letter

[awalterschulze]

In test_objects.proto I changed the field names to have a first letter as a capital.

message MsgWithOneof {
  oneof union {
    string Title = 1;
    int64 Salary = 2;
  }
}

This produces an error

unknown field "salary" in jsonpb.MsgWithOneof

So technically the fieldname isn't salary anymore, it is Salary, but this is what it marshals to and this is what the tags say it should be

type MsgWithOneof_Salary struct {
    Salary int64 `protobuf:"varint,2,opt,name=Salary,json=salary,oneof"`
}

[stevvooe]

We actually saw this issue, as well. It was very odd, as it only worked with the specific package from the unit tests. Once MsgWithOneof is pulled out of the package, it will not deserialize the json with a oneof field.

If more details are required, please let me know.

cc @aluzzardi

[dsymonds]

jsonpb is specified to accept either the .proto original name, or the camelCase name. In this case, that means the acceptable set should be {Salary,salary}. It does indeed sound like a bug.

It looks like a bug specific to oneofs.