List OPTIONS in OPTIONS responses for @RequestMapping

Issue: SPR-16513

Author: rstoyanchev

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/RequestMappingInfoHandlerMapping.java

@@ -365,6 +365,7 @@ private static Set<HttpMethod> initAllowedHttpMethods(Set<HttpMethod> declaredMe
 				if (result.contains(HttpMethod.GET)) {
 					result.add(HttpMethod.HEAD);
 				}
+				result.add(HttpMethod.OPTIONS);
 				return result;
 			}
 		}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/RequestMappingInfoHandlerMappingTests.java

@@ -195,8 +195,8 @@ public void getHandlerHttpOptions() throws Exception {
 		List<HttpMethod> allMethodExceptTrace = new ArrayList<>(Arrays.asList(HttpMethod.values()));
 		allMethodExceptTrace.remove(HttpMethod.TRACE);
 
-		testHttpOptions("/foo", EnumSet.of(HttpMethod.GET, HttpMethod.HEAD));
-		testHttpOptions("/person/1", EnumSet.of(HttpMethod.PUT));
+		testHttpOptions("/foo", EnumSet.of(HttpMethod.GET, HttpMethod.HEAD, HttpMethod.OPTIONS));
+		testHttpOptions("/person/1", EnumSet.of(HttpMethod.PUT, HttpMethod.OPTIONS));
 		testHttpOptions("/persons", EnumSet.copyOf(allMethodExceptTrace));
 		testHttpOptions("/something", EnumSet.of(HttpMethod.PUT, HttpMethod.POST));
 	}

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

@@ -443,6 +443,7 @@ private static Set<HttpMethod> initAllowedHttpMethods(Set<String> declaredMethod
 						result.add(HttpMethod.HEAD);
 					}
 				}
+				result.add(HttpMethod.OPTIONS);
 			}
 			return result;
 		}

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/RequestMappingInfoHandlerMappingTests.java

@@ -172,8 +172,8 @@ public void getHandlerMediaTypeNotSupported() throws Exception {
 
 	@Test
 	public void getHandlerHttpOptions() throws Exception {
-		testHttpOptions("/foo", "GET,HEAD");
-		testHttpOptions("/person/1", "PUT");
+		testHttpOptions("/foo", "GET,HEAD,OPTIONS");
+		testHttpOptions("/person/1", "PUT,OPTIONS");
 		testHttpOptions("/persons", "GET,HEAD,POST,PUT,PATCH,DELETE,OPTIONS");
 		testHttpOptions("/something", "PUT,POST");
 	}

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ServletAnnotationControllerHandlerMethodTests.java

@@ -1776,7 +1776,7 @@ public void httpOptions() throws Exception {
 		getServlet().service(request, response);
 
 		assertEquals(200, response.getStatus());
-		assertEquals("GET,HEAD", response.getHeader("Allow"));
+		assertEquals("GET,HEAD,OPTIONS", response.getHeader("Allow"));
 		assertTrue(response.getContentAsByteArray().length == 0);
 	}