public Review getReview(Hotel hotel, int reviewNumber) {
   Assert.notNull(hotel, "Hotel must not be null");
   return reviewRepository.findByHotelAndIndex(hotel, reviewNumber);
 }
 public Page<Review> getReviews(Hotel hotel, Pageable pageable) {
   Assert.notNull(hotel, "Hotel must not be null");
   return reviewRepository.findByHotel(hotel, pageable);
 }