final public function get_user_array(Array $additional_fields = array())
	{
		$user = array(
			'email'        => $this->get_email(),
			'screen_name'  => $this->get_screen_name(),
			'groups'       => $this->get_groups(),
		);

		$additional_fields = array_merge($this->config['additional_fields'], $additional_fields);
		foreach($additional_fields as $af)
		{
			// only works if it actually can be fetched through a get_ method
			if (is_callable(array($this, $method = 'get_'.$af)))
			{
				$user[$af] = $this->$method();
			}
		}
		return $user;
	}