title: URI must be a string or UriInterface in laravel php
body: <p>Currently, I m having a strange issue on php code. I am trying to acess my external service through rest api via <code>GuzzleHttp\Client</code> as rest client.
  When I assigned <code>$url</code> as the following code:</p>
  
  <pre><code>$url ="http://xxx.xxx.xxx.xxx/auth";
  Log::debug($url);
  $request = new Request("POST", $url, [], json_encode($object));
  return self::getClient()-&gt;post($request);
  </code></pre>
  
  <p>It will print the following log</p>
  
  <pre><code>[2018-12-09 20:46:21] local.DEBUG: http://xxx.xxx.xxx.xxx/auth
  </code></pre>
  
  <p>which will result in following exception</p>
  
  <pre><code>InvalidArgumentException URI must be a string or UriInterface
  </code></pre>