Short-hand Protobuf Object Instantiation

Is there an easy way to generate a protobuf given a native Javascript Object? What I'd like to do is this:

```
// pubsub.proto

message PublishCloudEventInput {
string clientMutationId = 1;
string id = 2;
}

message PublishCloudEventResponse {
string clientMutationId = 1;
}

service Pubsub {
rpc Publish(stream PublishCloudEventInput) returns (stream PublishCloudEventResponse);
}
```

```
// client.js

const grpc = require('grpc')

const messages = require('./build/pubsub_pb')
const services = require('./build/pubsub_grpc_pb')

var client = new services.PubsubClient('127.0.0.1:5000', grpc.credentials.createInsecure())

const publishStream = client.publish()
const p = new messages.PublishCloudEventInput({
clientMutationId: '1234',
id: '5678'
})
```
rather than
```
const p = new messages.PublishCloudEventInput()
p.setClientmutationid('1234')
p.setId('5678')
```