import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;import java.util.*;@RestController public class CheckoutController{@GetMapping("/checkout") public Map<String,Object>checkout(@RequestParam String products,@RequestParam(required=false) String coupon){// Parse products Map<String,Integer>productQuantities=new HashMap<>();for (String productEntry :products.split(",")){String[] parts=productEntry.split(":");productQuantities.put(parts[0],// Product ID Integer.parseInt(parts[1]) // Quantity)}// Build result Map<String,Object>result=new HashMap<>();result.put("products",productQuantities);result.put("coupon",coupon !=null ? coupon:"No coupon applied");return result}}