private static function _autoUpdateFromFields(&$fields)
    {
        $addKeywords = [null, null];
        $removeKeywords = [null, null];

        if (isset($fields->add) && isset($fields->add->first_word)) {
            $addKeywords[0] = $fields->add->first_word;
        }

        if (isset($fields->add) && isset($fields->add->second_word)) {
            $addKeywords[1] = $fields->add->second_word;
        }

        if (isset($fields->remove) && isset($fields->remove->first_word)) {
            $removeKeywords[0] = $fields->remove->first_word;
        }

        if (isset($fields->remove) && isset($fields->remove->second_word)) {
            $removeKeywords[1] = $fields->remove->second_word;
        }

        return new Api\GroupAutoUpdate(
            $fields->to, $addKeywords, $removeKeywords
        );
    }