protected function getHighestAuthenticationServicePriority()
    {
        $highestPriority = 0;

        if (is_array($GLOBALS['T3_SERVICES']['auth'])) {
            foreach ($GLOBALS['T3_SERVICES']['auth'] as $service) {
                if ($service['priority'] > $highestPriority) {
                    $highestPriority = $service['priority'];
                }
            }
        }

        return $highestPriority;
    }