@Entity
public class Todo {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private String title;
  private boolean done;
}

@RestController
@RequestMapping("/api/todos")
public class TodoController {
  private final TodoService service;

  public TodoController(TodoService service) {
    this.service = service;
  }

  @GetMapping
  public List<Todo> list() {
    return service.findAll();
  }
}

public interface TodoRepository extends JpaRepository<Todo, Long> {
}

@Service
public class TodoService {
  private final TodoRepository repository;

  public TodoService(TodoRepository repository) {
    this.repository = repository;
  }

  public List<Todo> findAll() {
    return repository.findAll();
  }
}