SPR-7381 - HTTP headers returned as part of ResponseEntity(MultiValueMap<String, String> headers, HttpStatus statusCode) are ignored when using this constructor

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/annotation/AnnotationMethodHandlerAdapter.java

@@ -938,6 +938,10 @@ public class AnnotationMethodHandlerAdapter extends WebContentGenerator
 			if (body != null) {
 				writeWithMessageConverters(body, inputMessage, outputMessage);
 			}
+			else {
+				// flush headers
+				outputMessage.getBody();
+			}
 		}
 
 		@SuppressWarnings("unchecked")

org.springframework.web.servlet/src/test/java/org/springframework/web/servlet/mvc/annotation/ServletAnnotationControllerTests.java

@@ -1212,6 +1212,7 @@ public class ServletAnnotationControllerTests {
 		request = new MockHttpServletRequest("PUT", "/bar");
 		response = new MockHttpServletResponse();
 		servlet.service(request, response);
+		assertEquals("MyValue", response.getHeader("MyResponseHeader"));
 		assertEquals(404, response.getStatus());
 	}
 
@@ -2716,7 +2717,9 @@ public class ServletAnnotationControllerTests {
 
 		@RequestMapping("/bar")
 		public ResponseEntity<String> bar() {
-			return new ResponseEntity<String>(new HttpHeaders(), HttpStatus.NOT_FOUND);
+			HttpHeaders responseHeaders = new HttpHeaders();
+			responseHeaders.set("MyResponseHeader", "MyValue");
+			return new ResponseEntity<String>(responseHeaders, HttpStatus.NOT_FOUND);
 		}
 
 	}