eZ\Publish\Core\Repository\URLAliasService::selectAliasLanguageCode PHP Method

    protected function selectAliasLanguageCode(SPIURLAlias $spiUrlAlias, $languageCode, $showAllTranslations, $prioritizedLanguageList)
    {
        if (isset($languageCode) && !in_array($languageCode, $spiUrlAlias->languageCodes)) {
            return false;
        }
        foreach ($prioritizedLanguageList as $languageCode) {
            if (in_array($languageCode, $spiUrlAlias->languageCodes)) {
                return $languageCode;
            }
        }
        if ($spiUrlAlias->alwaysAvailable || $showAllTranslations) {
            $lastLevelData = end($spiUrlAlias->pathData);
            reset($lastLevelData['translations']);
            return key($lastLevelData['translations']);
        }
        return false;
    }