@Override
    void merge(Author oldEntity, Author newEntity) {
        if(!oldEntity.getFirstName().equals(newEntity.getFirstName())) oldEntity.setFirstName(newEntity.getFirstName());
        if(!oldEntity.getLastName().equals(newEntity.getLastName())) oldEntity.setLastName(newEntity.getLastName());
        if(oldEntity.getBirthDate() != newEntity.getBirthDate()) oldEntity.setBirthDate(newEntity.getBirthDate());
        if(!oldEntity.getCountry().equals(newEntity.getCountry())) oldEntity.setCountry(newEntity.getCountry());
    }