public function can_upgrade($type, $version) {
        if ($type == 'offline' && $version >= 2011112900) {
            return true;
        }
        foreach ($this->submissionplugins as $plugin) {
            if ($plugin->can_upgrade($type, $version)) {
                return true;
            }
        }
        foreach ($this->feedbackplugins as $plugin) {
            if ($plugin->can_upgrade($type, $version)) {
                return true;
            }
        }
        return false;
    }