private void mergeGuests(Set<Guest> guests) {
        LOG.debug("start mergeGuests");
        for (Guest guest : guests) {
            Guest storedGuest = applicationService.fetch(guest.getId(), Guest.class);
            if (storedGuest != null) {
                if (isNotTrue(storedGuest.getClientChangedByPortware())) {
                    guest.setClient(mergeClient(storedGuest.getClient()));
                }
                for (TravelClass travelClass : guest.getTravelClasses()) {
                    TravelClass storedTravelClass = getGuestTravelClassWithSailPackageSeawareId(storedGuest,
                            travelClass.getSailPackage().getSeawareId());
                    if (storedTravelClass != null) {
                        storedTravelClass.setCabin(travelClass.getCabin());
                        storedTravelClass.setGuestCheckedIn(travelClass.getGuestCheckedIn());
                        applicationService.merge(storedTravelClass);
                    } else {
                        applicationService.merge(travelClass);
                    }
                }
            } else {
                guest.setClient(mergeClient(guest.getClient()));
                Set<TravelClass> travelClasses = new HashSet<>(guest.getTravelClasses());
                guest.setTravelClasses(null);
                applicationService.merge(guest);
                for (TravelClass travelClass : travelClasses) {
                    applicationService.merge(travelClass);
                }
            }

        }
    }