private Client mergeClient(Client client) {
        LOG.debug("start mergeClient");
        if (client == null) {
            return null;
        }
        LOG.debug("merging client with pwId[" + client.getId() + "] sw_id[" + client.getSeawareId() + "]");
        Client storedClient = applicationDao.fetchByRestrictions(Client.class, new Restriction("seawareId", client.getSeawareId()));
        if (storedClient != null && !storedClient.getId().equals(client.getId())) {
            LOG.debug("storedClient client with pwId[" + storedClient.getId() + "] sw_id[" + storedClient.getSeawareId() + "]");
            for (Guest guest : storedClient.getGuests()) {
                guest.setClient(null);
                applicationService.update(guest);
            }
            for (Reservation reservation : storedClient.getReservations()) {
                reservation.setReservationContact(null);
                applicationService.update(reservation);
            }
            storedClient.getGuests().clear();
            storedClient.getReservations().clear();
            applicationService.delete(storedClient.getId(), Client.class);
        }
        LOG.debug("client was merged pwId[" + client.getId() + "] sw_id[" + client.getSeawareId() + "]");
        return applicationService.merge(client);
    }