Update database with Fluent API approach

public Book book(Long bookId, Book book) {
    return bookRepository.findById(bookId).
            map(foundBook -> {
                foundBook.setName(book.getName());
                foundBook.setDescription(book.getDescription());
                foundBook.setImageUrl(book.getImageUrl());
                return bookRepository.save(foundBook);
            })
            .orElseThrow(() -> new BookNotFoundException(bookId));
}