What is native API versioning in Spring Boot 4 and how do you use it?

// Spring Boot 3: manual versioning (repetitive and fragile)
@RestController
@RequestMapping("/api/v1/products")
public class ProductControllerV1 { ... }

@RestController
@RequestMapping("/api/v2/products")
public class ProductControllerV2 { ... }

// Spring Boot 4: native versioning
@RestController
@RequestMapping("/api/products")
public class ProductController {

    @GetMapping(path = "/{id}", version = "1.0")
    public ProductV1 getProductV1(@PathVariable String id) {
        return productService.findV1(id);
    }

    @GetMapping(path = "/{id}", version = "2.0")
    public ProductV2 getProductV2(@PathVariable String id) {
        return productService.findV2(id);
    }
}

// Configuration in application.properties:
# Header-based versioning:
spring.mvc.apiversion.use-header=X-API-Version
spring.mvc.apiversion.default=1
# Request: GET /api/products/123 with header X-API-Version: 2
# Routes to: getProductV2

// Deprecation handling (RFC 9745 compliant):
@GetMapping(path = "/{id}", version = "1.0", deprecated = true)
public ProductV1 getProductV1(@PathVariable String id) {
    // Spring automatically adds Deprecation response header
    return productService.findV1(id);
}