使用protobuf子字段解组JSON消息

Question

I'm receiving a JSON blob from a Kubernetes API that contains a type that includes a protobuf subfield. Since that protobuf includes oneof fields, I have to use golang/protobuf/jsonpb and not encoding/json.

I've reproduced this simply here:

client.proto

message Latency {
  oneof latency_type {
    StaticLatency static = 1;
    NormalLatency normal = 2;
  }
}

client.go:

type Metadata struct {
    Name string `json:"name,omitempty"`
}

type LatencyWrapper struct {
    Meta    Metadata `json:"meta"`
    Latency Latency  `json:"latency"`
}

How can I unmarshal this message? I think I want something like this:

func (lw *LatencyWrapper) UnmarshalJSON(b []byte) error {
    var parts map[string]string = Something()

    json.Unmarshal(parts["meta"], &lw.meta)
    jsonpb.Unmarshal(parts["latency"], &lw.latency)

    return nil
}

Thanks for your help!

Michael