Use HttpRequest.getMethodValue

This commit uses the newly introduced HttpRequest.getMethodValue in
the webflux module.

Issue: SPR-15545

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/InvalidHttpMethodIntegrationTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.reactive.function.server;
+
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * @author Arjen Poutsma
+ */
+public class InvalidHttpMethodIntegrationTests extends AbstractRouterFunctionIntegrationTests {
+
+	@Override
+	protected RouterFunction<?> routerFunction() {
+		return RouterFunctions.route(RequestPredicates.GET("/"),
+				request -> ServerResponse.ok().syncBody("FOO"))
+				.andRoute(RequestPredicates.all(),
+						request -> ServerResponse.ok().syncBody("BAR"));
+	}
+
+	@Test
+	public void invalidHttpMethod() throws Exception {
+		OkHttpClient client = new OkHttpClient();
+
+		Request request = new Request.Builder()
+				.method("BAZ", null)
+				.url("http://localhost:" + port + "/")
+				.build();
+
+		try (Response response = client.newCall(request).execute()) {
+			assertEquals("BAR", response.body().string());
+		}
+	}
+}