Add CONNECT constant to HttpMethod

spring-web/src/main/java/org/springframework/http/HttpMethod.java

@@ -71,6 +71,12 @@ public final class HttpMethod implements Comparable<HttpMethod>, Serializable {
 	 */
 	public static final HttpMethod DELETE = new HttpMethod("DELETE");
 
+	/**
+	 * The HTTP method {@code CONNECT}.
+	 * @see <a href="https://www.rfc-editor.org/rfc/rfc9110.html#section-9.3.6">RFC 9110, section 9.3.6</a>
+	 */
+	public static final HttpMethod CONNECT = new HttpMethod("CONNECT");
+
 	/**
 	 * The HTTP method {@code OPTIONS}.
 	 * @see <a href="https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.2">HTTP 1.1, section 9.2</a>
@@ -83,7 +89,7 @@ public final class HttpMethod implements Comparable<HttpMethod>, Serializable {
 	 */
 	public static final HttpMethod TRACE = new HttpMethod("TRACE");
 
-	private static final HttpMethod[] values = new HttpMethod[] { GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE };
+	private static final HttpMethod[] values = new HttpMethod[] { GET, HEAD, POST, PUT, PATCH, DELETE, CONNECT, OPTIONS, TRACE };
 
 
 	private final String name;
@@ -97,7 +103,7 @@ private HttpMethod(String name) {
 	 * Returns an array containing the standard HTTP methods. Specifically,
 	 * this method returns an array containing {@link #GET}, {@link #HEAD},
 	 * {@link #POST}, {@link #PUT}, {@link #PATCH}, {@link #DELETE},
-	 * {@link #OPTIONS}, and {@link #TRACE}.
+	 * {@link #CONNECT}, {@link #OPTIONS}, and {@link #TRACE}.
 	 *
 	 * <p>Note that the returned value does not include any HTTP methods defined
 	 * in WebDav.
@@ -122,6 +128,7 @@ public static HttpMethod valueOf(String method) {
 			case "PUT" -> PUT;
 			case "PATCH" -> PATCH;
 			case "DELETE" -> DELETE;
+			case "CONNECT" -> CONNECT;
 			case "OPTIONS" -> OPTIONS;
 			case "TRACE" -> TRACE;
 			default -> new HttpMethod(method);

spring-web/src/test/java/org/springframework/http/HttpMethodTests.java

@@ -44,12 +44,12 @@ void comparison() {
 	void values() {
 		HttpMethod[] values = HttpMethod.values();
 		assertThat(values).containsExactly(HttpMethod.GET, HttpMethod.HEAD, HttpMethod.POST, HttpMethod.PUT,
-				HttpMethod.PATCH, HttpMethod.DELETE, HttpMethod.OPTIONS, HttpMethod.TRACE);
+				HttpMethod.PATCH, HttpMethod.DELETE, HttpMethod.CONNECT, HttpMethod.OPTIONS, HttpMethod.TRACE);
 
 		// check defensive copy
 		values[0] = HttpMethod.POST;
 		assertThat(HttpMethod.values()).containsExactly(HttpMethod.GET, HttpMethod.HEAD, HttpMethod.POST, HttpMethod.PUT,
-				HttpMethod.PATCH, HttpMethod.DELETE, HttpMethod.OPTIONS, HttpMethod.TRACE);
+				HttpMethod.PATCH, HttpMethod.DELETE, HttpMethod.CONNECT, HttpMethod.OPTIONS, HttpMethod.TRACE);
 	}
 
 	@Test

spring-web/src/test/java/org/springframework/http/client/reactive/ClientHttpConnectorTests.java

@@ -271,6 +271,9 @@ static List<Arguments> methodsWithConnectors() {
 		List<Arguments> result = new ArrayList<>();
 		for (Named<ClientHttpConnector> connector : connectors()) {
 			for (HttpMethod method : HttpMethod.values()) {
+				if (HttpMethod.CONNECT.equals(method) && List.of("HttpComponents", "Jdk").contains(connector.getName())) {
+					continue;
+				}
 				result.add(Arguments.of(connector, method));
 			}
 		}

spring-web/src/test/java/org/springframework/web/bind/annotation/RequestMethodTests.java

@@ -41,6 +41,10 @@ void resolveString() {
 	@Test
 	void resolveHttpMethod() {
 		for (HttpMethod httpMethod : HttpMethod.values()) {
+			if (HttpMethod.CONNECT.equals(httpMethod)) {
+				assertThat(RequestMethod.resolve(httpMethod)).isNull();
+				continue;
+			}
 			RequestMethod requestMethod = RequestMethod.resolve(httpMethod);
 			assertThat(requestMethod).isNotNull();
 			assertThat(requestMethod.name()).isEqualTo(httpMethod.name());

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

@@ -517,7 +517,7 @@ private static Set<HttpMethod> initAllowedHttpMethods(Set<String> declaredMethod
 			Set<HttpMethod> result = CollectionUtils.newLinkedHashSet(declaredMethods.size());
 			if (declaredMethods.isEmpty()) {
 				for (HttpMethod method : HttpMethod.values()) {
-					if (method != HttpMethod.TRACE) {
+					if (method != HttpMethod.TRACE && method != HttpMethod.CONNECT) {
 						result.add(method);
 					}
 				}

spring-webmvc/src/main/java/org/springframework/web/servlet/support/WebContentGenerator.java

@@ -146,7 +146,7 @@ private void initAllowHeader() {
 		if (this.supportedMethods == null) {
 			allowedMethods = new ArrayList<>(HttpMethod.values().length - 1);
 			for (HttpMethod method : HttpMethod.values()) {
-				if (method != HttpMethod.TRACE) {
+				if (method != HttpMethod.TRACE && method != HttpMethod.CONNECT) {
 					allowedMethods.add(method.name());
 				}
 			}