@PutMapping("/create") public Book create(Map<String, Object> map) throws Exception { System.out.println("Check if book exists " + map); Book book = new ObjectMapper().convertValue(map, Book.class); Book b = repo.findByTitle(book.getTitle()); if (b != null) { throw new Exception("Book already exists"); } book.setId(UUID.randomUUID().toString()); repo.save(book); log.debug("Book {} by {} is created with id {}", book.getTitle(), book.getAuthor(), book.getId()); return book; } public BookStoreController(BooksRepository repo, Boolean bool, List<String> keys) { this.repo = repo; if (Boolean.TRUE.equals(bool)) { // check first key if(keys != null && !keys.isEmpty()){ String firstKey = keys.get(0); if (firstKey == "public") { for (String key : keys){ // ... some logic log.debug("Using key {}", key); }; } } } }