Polish

Issue: SPR-11129

Author: rstoyanchev

spring-web/src/main/java/org/springframework/web/bind/annotation/RequestMapping.java

@@ -195,6 +195,8 @@
  * The entity body will be converted to the response stream using
  * {@linkplain org.springframework.http.converter.HttpMessageConverter message
  * converters}.
+ * <li>An {@link org.springframework.http.HttpHeaders HttpHeaders} object to
+ * return a response with no body.</li>
  * <li>A {@link Callable} which is used by Spring MVC to obtain the return
  * value asynchronously in a separate thread transparently managed by Spring MVC
  * on behalf of the application.

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java

@@ -41,17 +41,18 @@ public boolean supportsReturnType(MethodParameter returnType) {
 
 	@Override
 	public void handleReturnValue(Object returnValue, MethodParameter returnType,
-								  ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
+			ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
+
 		mavContainer.setRequestHandled(true);
 
 		Assert.isInstanceOf(HttpHeaders.class, returnValue);
 		HttpHeaders headers = (HttpHeaders) returnValue;
 
-		HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class);
-		ServletServerHttpResponse outputMessage = new ServletServerHttpResponse(response);
 		if (!headers.isEmpty()) {
+			HttpServletResponse servletResponse = webRequest.getNativeResponse(HttpServletResponse.class);
+			ServletServerHttpResponse outputMessage = new ServletServerHttpResponse(servletResponse);
 			outputMessage.getHeaders().putAll(headers);
+			outputMessage.getBody(); // flush headers
 		}
-		outputMessage.getBody(); // flush headers
 	}
 }

src/asciidoc/index.adoc

@@ -29033,9 +29033,10 @@ The following are the supported return types:
 * If the method is annotated with `@ResponseBody`, the return type is written to the
   response HTTP body. The return value will be converted to the declared method argument
   type using `HttpMessageConverter` s. See <<mvc-ann-responsebody>>.
-* A `HttpEntity<?>` or `ResponseEntity<?>` object to provide access to the Servlet
+* An `HttpEntity<?>` or `ResponseEntity<?>` object to provide access to the Servlet
   response HTTP headers and contents. The entity body will be converted to the response
   stream using `HttpMessageConverter` s. See <<mvc-ann-httpentity>>.
+* An `HttpHeaders` object to return a response with no body.
 * A `Callable<?>` can be returned when the application wants to produce the return value
   asynchronously in a thread managed by Spring MVC.
 * A `DeferredResult<?>` can be returned when the application wants to produce the return