Graphileon Proxy feature - how to pass credentials

I have one question on the proxy feature of Graphileon. How can we pass credentials like basic auth to Graphileon proxy request hitting a backend API

var body = JSON.stringify({
                    url: "http://localhost:8080/api",
                    method: "POST",
                    body: {key1 : "value1"}
                })

$.ajax({
url: "/proxy",
method: "POST",
data: body
})

You can do it like this:

var body = JSON.stringify({
                    url: "http://localhost:8080/api",
                    method: "POST",
                    body: {key1 : "value1"},
                    auth: {
                        user: '...',
                        pass: '...',
                        sendImmediately: false | true
                    }
                })

or

var body = JSON.stringify({
                    url: "http://<username>:<password>@localhost:8080/api",
                    method: "POST",
                    body: {key1 : "value1"},
           })

or

var body = JSON.stringify({
                    url: "http://localhost:8080/api",
                    method: "POST",
                    body: {key1 : "value1"},
                    headers: {
                        'Authorization': 'Basic ' + btoa('<username>:<password>')
                    }
    }