Make use of new GetMapping and PostMapping annotations

Closes gh-5277

spring-boot-samples/spring-boot-sample-undertow/src/main/java/sample/undertow/web/SampleController.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import java.util.concurrent.Callable;
 import sample.undertow.service.HelloWorldService;
 
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 @RestController
@@ -30,12 +30,12 @@ public class SampleController {
 	@Autowired
 	private HelloWorldService helloWorldService;
 
-	@RequestMapping("/")
+	@GetMapping("/")
 	public String helloWorld() {
 		return this.helloWorldService.getHelloMessage();
 	}
 
-	@RequestMapping("/async")
+	@GetMapping("/async")
 	public Callable<String> helloWorldAsync() {
 		return new Callable<String>() {