public function serialize(Keyword $keyword, array $options = [])
    {
        $serialized = [
            'text' => $keyword->getText(),
            'caseSensitive' => $keyword->isCaseSensitive(),
            'score' => $keyword->getScore(),
        ];

        if ($keyword->getFeedback()) {
            $serialized['feedback'] = $keyword->getFeedback();
        }

        return $serialized;
    }