Deprecate JettyWebSocketClient in favor of StandardWebSocketClient

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

Closes gh-29576

spring-webflux/src/main/java/org/springframework/web/reactive/socket/client/JettyWebSocketClient.java

@@ -39,6 +39,7 @@ import org.springframework.web.reactive.socket.adapter.JettyWebSocketSession;
 /**
  * A {@link WebSocketClient} implementation for use with Jetty
  * {@link org.eclipse.jetty.websocket.client.WebSocketClient}.
+ * Only supported on Jetty 11, superseded by {@link StandardWebSocketClient}.
  *
  * <p><strong>Note: </strong> the Jetty {@code WebSocketClient} requires
  * lifecycle management and must be started and stopped. This is automatically
@@ -49,7 +50,9 @@ import org.springframework.web.reactive.socket.adapter.JettyWebSocketSession;
  * @author Rossen Stoyanchev
  * @author Juergen Hoeller
  * @since 5.0
+ * @deprecated as of 6.0.3, in favor of {@link StandardWebSocketClient}
  */
+@Deprecated(since = "6.0.3", forRemoval = true)
 public class JettyWebSocketClient implements WebSocketClient, Lifecycle {
 
 	private static final Log logger = LogFactory.getLog(JettyWebSocketClient.class);