Deprecate JettyWebSocketClient in favor of StandardWebSocketClient

JettyWebSocketClient only supported on Jetty 11, to be phased out.

Closes gh-29576

spring-websocket/src/main/java/org/springframework/web/socket/client/jetty/JettyWebSocketClient.java

@@ -45,7 +45,8 @@ import org.springframework.web.socket.client.AbstractWebSocketClient;
 
 /**
  * Initiates WebSocket requests to a WebSocket server programmatically
- * through the Jetty WebSocket API.
+ * through the Jetty WebSocket API. Only supported on Jetty 11, superseded by
+ * {@link org.springframework.web.socket.client.standard.StandardWebSocketClient}.
  *
  * <p>As of 4.1 this class implements {@link Lifecycle} rather than
  * {@link org.springframework.context.SmartLifecycle}. Use
@@ -55,7 +56,10 @@ import org.springframework.web.socket.client.AbstractWebSocketClient;
  * @author Rossen Stoyanchev
  * @author Juergen Hoeller
  * @since 4.0
+ * @deprecated as of 6.0.3, in favor of
+ * {@link org.springframework.web.socket.client.standard.StandardWebSocketClient}
  */
+@Deprecated(since = "6.0.3", forRemoval = true)
 public class JettyWebSocketClient extends AbstractWebSocketClient implements Lifecycle {
 
 	private final org.eclipse.jetty.websocket.client.WebSocketClient client;

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

@@ -65,6 +65,7 @@ public abstract class AbstractWebSocketIntegrationTests {
 		upgradeStrategyConfigTypes.put(UndertowTestServer.class, UndertowUpgradeStrategyConfig.class);
 	}
 
+	@SuppressWarnings("removal")
 	static Stream<Arguments> argumentsFactory() {
 		return Stream.of(
 				arguments(named("Jetty", new JettyWebSocketTestServer()), named("Jetty", new JettyWebSocketClient())),

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/client/JettySockJsIntegrationTests.java

@@ -42,6 +42,7 @@ class JettySockJsIntegrationTests extends AbstractSockJsIntegrationTests {
 		return new JettyWebSocketTestServer();
 	}
 
+	@SuppressWarnings("removal")
 	@Override
 	protected Transport createWebSocketTransport() {
 		return new WebSocketTransport(new JettyWebSocketClient());