Config::getAvailableDefaultLanguages

static function getAvailableDefaultLanguages(): array 
{
	static $languages;
	if ($languages === null)
	{
		$languages = [];
		$langDirList = new MainIODirectory(MainApplication::getDocumentRoot(). '/bitrix/modules/main/lang/');
		foreach ($langDirList->getChildren() as $langDir)
		{
			$langId = $langDir->getName();
			if (in_array($langId, TranslateIGNORE_FS_NAMES, true) || !$langDir->isDirectory())
			{
				continue;
			}
			$languages[] = $langId;
		}
	}

	return $languages;
}