How to send custom headers to graphql server with relay?

Question

I've seen the docs re injecting a new DefaultNetworkLayer, but I don't seem to be able to send custom headers. Here's my code:

var headers = new Headers();
headers.append('Authorization', 'Basic hellotheretestheader');   

Relay.injectNetworkLayer(
    new Relay.DefaultNetworkLayer('/graphql', {
        headers: headers
    })
);

Why doesn't this work?

Answer 1

Ah the answer is:

Relay.injectNetworkLayer(
  new Relay.DefaultNetworkLayer('/graphql', {
    headers: {
        'Authorization': 'Basic hellotheretestheader'
    }
  })
);