/lib/classes/oauth2/client.php 

Method get_userinfo

When requesting user information a token is required to authenticate any request. Currently, there is only a request to the userinfo endpoint assigned in the settings. The snippet below is  a suggestion but does use a querystring. Bearer token should also be supported.

// Suggested edit around line 247 in /lib/classes/oauth2/client.php 

$accesstoken = $this->get_accesstoken();

$params = array(

   'access_token' => $accesstoken->token

);

$response = $this->get( $url, $params );