How do you build REST APIs with Spring Boot 4 using @RestController?

import jakarta.validation.Valid;
import jakarta.validation.constraints.*;
import org.jspecify.annotations.Nullable;

@RestController
@RequestMapping("/api/orders")
@Validated
public class OrderController {

    private final OrderService service;

    public OrderController(OrderService service) {
        this.service = service;
    }

    // GET all with pagination
    @GetMapping
    public Page<OrderDto> listOrders(
            @RequestParam(defaultValue = "0") int page,
            @RequestParam(defaultValue = "20") int size) {
        return service.findAll(PageRequest.of(page, size));
    }

    // GET by ID
    @GetMapping("/{id}")
    public ResponseEntity<OrderDto> getOrder(@PathVariable String id) {
        return service.findById(id)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    // POST: create new order
    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    public OrderDto createOrder(@Valid @RequestBody CreateOrderRequest request) {
        return service.create(request);
    }

    // PUT: full update
    @PutMapping("/{id}")
    public OrderDto updateOrder(
            @PathVariable String id,
            @Valid @RequestBody UpdateOrderRequest request) {
        return service.update(id, request);
    }

    // DELETE
    @DeleteMapping("/{id}")
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public void deleteOrder(@PathVariable String id) {
        service.delete(id);
    }

    // Native API versioning (Spring Boot 4):
    @GetMapping(path = "/{id}", version = "2.0")
    public OrderDtoV2 getOrderV2(@PathVariable String id) {
        return service.findByIdV2(id);
    }

    // Global exception handler:
    @ExceptionHandler(OrderNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public ErrorResponse handleNotFound(OrderNotFoundException ex) {
        return new ErrorResponse("ORDER_NOT_FOUND", ex.getMessage());
    }
}