protected static function convertSynonymFileLineForImport($line, $synonymList) : array
    {
        $lineParts = GeneralUtility::trimExplode('=>', $line, true);

        if (isset($lineParts[1])) {
            $baseWord = mb_strtolower($lineParts[0]);
            $synonyms = GeneralUtility::trimExplode(',', mb_strtolower($lineParts[1]), true);
        } else {
            $synonyms = GeneralUtility::trimExplode(',', mb_strtolower($lineParts[0]), true);
            $baseWord = mb_strtolower(reset($synonyms));
        }
        $synonymList[$baseWord] = $synonyms;

        return $synonymList;
    }