Spring MVC: implementing Handling JSON Response for Nested Collections with @ResponseBody
I'm working with a question with returning a JSON response for a nested collection in my Spring MVC application. I'm using Spring 5.3.10 and Jackson for JSON serialization. In my controller, I have an endpoint that is supposed to return a list of `User` objects, each containing a list of `Address` objects. Here's the relevant part of my code: ```java @GetMapping("/users") @ResponseBody public List<User> getUsers() { List<User> users = new ArrayList<>(); User user1 = new User("Alice", Arrays.asList(new Address("123 Main St", "Springfield"))); User user2 = new User("Bob", Arrays.asList(new Address("456 Elm St", "Shelbyville"))); users.add(user1); users.add(user2); return users; } ``` My `User` class looks like this: ```java public class User { private String name; private List<Address> addresses; // Constructor, getters and setters } ``` And my `Address` class: ```java public class Address { private String street; private String city; // Constructor, getters and setters } ``` The scenario is that when I hit the `/users` endpoint, I receive the following JSON response: ```json [ { "name": "Alice", "addresses": null }, { "name": "Bob", "addresses": null } ] ``` It seems like the `addresses` list is not being populated correctly. I've confirmed that the `User` and `Address` constructors are being called by adding some logging, and they are indeed creating the objects as expected. I also tried adding `@JsonManagedReference` and `@JsonBackReference` annotations to manage the serialization, but that didn't resolve my scenario either. I suspect it might be related to how the Jackson library is configured in my application context, but I'm not sure what exactly needs to be changed. Any insights on how to correctly serialize nested collections in this scenario would be greatly appreciated! This is part of a larger application I'm building. I'd really appreciate any guidance on this.