private function ensureHrefDefaultsToNull()
    {
        if (!($this->database->tableExists('tl_metamodel_translatedurl'))) {
            return;
        }

        foreach ($this->database->listFields('tl_metamodel_translatedurl', true) as $field) {
            if ('href' == $field['name'] && $field['type'] != 'index') {
                // Already updated?
                if ('NOT NULL' === $field['null']) {
                    $this->database->execute(
                        'ALTER TABLE `tl_metamodel_translatedurl` CHANGE `href` `href` varchar(255) NULL;'
                    );
                    return;
                }
                // Found!
                break;
            }
        }
    }