public function getKeywords(array $languageCodes)
    {
        $keywords = [];

        foreach ($languageCodes as $languageCode) {
            if (isset($this->keywords[$languageCode])) {
                $keywords[$languageCode] = $this->keywords[$languageCode];
            }
        }

        if (empty($keywords)) {
            return [
                $this->mainLanguageCode => $this->getKeyword($this->mainLanguageCode),
            ];
        }

        return $keywords;
    }