xero guzzle attempt

<?php
$stack = HandlerStack::create();

$middleware = new Oauth1([
    'consumer_key'    => config('services.xero.key'),
    'consumer_secret' => config('services.xero.secret'),
]);
$stack->push($middleware);

$client = new Client([
    'base_uri' => 'https://api.xero.com/api.xro/2.0/',
    'handler' => $stack,
]);

$res = $client->request('GET', 'Contacts');
var_dump($res);