Minor fix in ServletResponseMethodArgumentResolver

Issues: SPR-8983

Author: rstoyanchev

Diff for: org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletResponseMethodArgumentResolver.java

@@ -61,8 +61,10 @@ public Object resolveArgument(
 			MethodParameter parameter, ModelAndViewContainer mavContainer,
 			NativeWebRequest webRequest, WebDataBinderFactory binderFactory)
 			throws IOException {
-		
-		mavContainer.setRequestHandled(true);
+
+		if (mavContainer != null) {
+			mavContainer.setRequestHandled(true);
+		}
 
 		HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class);
 		Class<?> paramType = parameter.getParameterType();

Diff for: org.springframework.web.servlet/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ServletResponseMethodArgumentResolverTests.java

@@ -70,6 +70,16 @@ public void servletResponse() throws Exception {
 		assertTrue(mavContainer.isRequestHandled());
 	}
 
+	// SPR-8983
+
+	public void servletResponseNoMavContainer() throws Exception {
+		MethodParameter servletResponseParameter = new MethodParameter(method, 0);
+		assertTrue("ServletResponse not supported", resolver.supportsParameter(servletResponseParameter));
+
+		Object result = resolver.resolveArgument(servletResponseParameter, null, webRequest, null);
+		assertSame("Invalid result", servletResponse, result);
+	}
+
 	@Test
 	public void outputStream() throws Exception {
 		MethodParameter outputStreamParameter = new MethodParameter(method, 1);