Prevent response updates if @ResponseStatus has reason

When @ResponseStatus has a reason and servletResponse.sendError() is
called, the response is committed and should no longer be written to.
After this change, the ServletInvocableHandlerMethod will mark the
response fully handled and will ignore any non-null return values.

Issue: SPR-9159

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

@@ -104,6 +104,10 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 				return;
 			}
 		}
+		else if (StringUtils.hasText(this.responseReason)) {
+			mavContainer.setRequestHandled(true);
+			return;
+		}
 
 		mavContainer.setRequestHandled(false);