Allow Undertow client in websocket integration tests

It seems to work.

spring-webflux/src/test/java/org/springframework/web/reactive/socket/AbstractWebSocketIntegrationTests.java

@@ -62,8 +62,6 @@ import org.springframework.web.reactive.socket.server.upgrade.TomcatRequestUpgra
 import org.springframework.web.reactive.socket.server.upgrade.UndertowRequestUpgradeStrategy;
 import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
 
-import static org.junit.Assume.assumeFalse;
-
 /**
  * Base class for WebSocket integration tests. Sub-classes must implement
  * {@link #getWebConfigClass()} to return Spring config class with (server-side)
@@ -117,15 +115,6 @@ public abstract class AbstractWebSocketIntegrationTests {
 
 	@Before
 	public void setup() throws Exception {
-		// TODO
-		// Caused by: java.io.IOException: Upgrade responses cannot have a transfer coding
-		// at org.xnio.http.HttpUpgrade$HttpUpgradeState.handleUpgrade(HttpUpgrade.java:490)
-		// at org.xnio.http.HttpUpgrade$HttpUpgradeState.access$1200(HttpUpgrade.java:165)
-		// at org.xnio.http.HttpUpgrade$HttpUpgradeState$UpgradeResultListener.handleEvent(HttpUpgrade.java:461)
-		// at org.xnio.http.HttpUpgrade$HttpUpgradeState$UpgradeResultListener.handleEvent(HttpUpgrade.java:400)
-		// at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
-
-		assumeFalse(this.client instanceof UndertowWebSocketClient);
 
 		this.server.setHandler(createHttpHandler());
 		this.server.afterPropertiesSet();

spring-webflux/src/test/java/org/springframework/web/reactive/socket/WebSocketIntegrationTests.java

@@ -63,7 +63,7 @@ public class WebSocketIntegrationTests extends AbstractWebSocketIntegrationTests
 		Flux<String> input = Flux.range(1, count).map(index -> "msg-" + index);
 		ReplayProcessor<Object> output = ReplayProcessor.create(count);
 
-		client.execute(getUrl("/echo"),
+		this.client.execute(getUrl("/echo"),
 				session -> {
 					logger.debug("Starting to send messages");
 					return session
@@ -87,7 +87,7 @@ public class WebSocketIntegrationTests extends AbstractWebSocketIntegrationTests
 		AtomicReference<HandshakeInfo> infoRef = new AtomicReference<>();
 		MonoProcessor<Object> output = MonoProcessor.create();
 
-		client.execute(getUrl("/sub-protocol"),
+		this.client.execute(getUrl("/sub-protocol"),
 				new WebSocketHandler() {
 					@Override
 					public List<String> getSubProtocols() {
@@ -117,7 +117,7 @@ public class WebSocketIntegrationTests extends AbstractWebSocketIntegrationTests
 		headers.add("my-header", "my-value");
 		MonoProcessor<Object> output = MonoProcessor.create();
 
-		client.execute(getUrl("/custom-header"), headers,
+		this.client.execute(getUrl("/custom-header"), headers,
 				session -> session.receive()
 						.map(WebSocketMessage::getPayloadAsText)
 						.subscribeWith(output)