public List<ZContact> getAllContacts(String optFolderId) throws ServiceException {
public List<ZContact> getAllContacts(String optFolderId, ContactSortBy sortBy, boolean sync, List<String> attrs) throws ServiceException {
    public List<ZContact> getAllContacts(String optFolderId) throws ServiceException {        XMLElement req = new XMLElement(MailService.GET_CONTACTS_REQUEST);        if (optFolderId != null)             req.addAttribute(MailService.A_FOLDER, optFolderId);        Element response = invoke(req);        List<ZContact> result = new ArrayList<ZContact>();        for (Element cn : response.listElements(MailService.E_CONTACT)) {            result.add(new ZSoapContact(cn));        }        return result;    }