Fixes typo in method 'convertHttpToWs'

The secure WebSocket protocol is "wss", not "wws".

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WebsocketRoutingFilter.java

@@ -104,7 +104,7 @@ public class WebsocketRoutingFilter implements GlobalFilter, Ordered {
 	private void changeSchemeIfIsWebSocketUpgrade(ServerWebExchange exchange) {
 		// Check the Upgrade
 		URI requestUrl = exchange.getRequiredAttribute(GATEWAY_REQUEST_URL_ATTR);
-		String scheme = requestUrl.getScheme();
+		String scheme = requestUrl.getScheme().toLowerCase();
 		String upgrade = exchange.getRequest().getHeaders().getUpgrade();
 		// change the scheme if the socket client send a "http" or "https"
 		if ("WebSocket".equalsIgnoreCase(upgrade) && ("http".equals(scheme) || "https".equals(scheme))) {
@@ -117,8 +117,9 @@ public class WebsocketRoutingFilter implements GlobalFilter, Ordered {
 		}
 	}
 
-	private String convertHttpToWs(String scheme) {
-		return "http".equals(scheme) ? "ws" : "https".equals(scheme) ? "wws" : scheme;
+	/* for testing */ static String convertHttpToWs(String scheme) {
+		scheme = scheme.toLowerCase();
+		return "http".equals(scheme) ? "ws" : "https".equals(scheme) ? "wss" : scheme;
 	}
 
 	private static class ProxyWebSocketHandler implements WebSocketHandler {

spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/filter/WebscketRoutingFilterTests.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2013-2018 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.cloud.gateway.filter;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.gateway.filter.WebsocketRoutingFilter.convertHttpToWs;
+
+public class WebscketRoutingFilterTests {
+
+	@Test
+	public void testConvertHttpToWs() {
+		assertThat(convertHttpToWs("http")).isEqualTo("ws");
+		assertThat(convertHttpToWs("HTTP")).isEqualTo("ws");
+		assertThat(convertHttpToWs("https")).isEqualTo("wss");
+		assertThat(convertHttpToWs("HTTPS")).isEqualTo("wss");
+		assertThat(convertHttpToWs("tcp")).isEqualTo("tcp");
+	}
+}