flaky test fixed

Author: Derrick2000

websockets-jsr/src/test/java/io/undertow/websockets/jsr/test/reconnect/ClientEndpointReconnectTestCase.java

@@ -113,6 +113,7 @@ public void testAnnotatedClientEndpoint() throws Exception {
         session.getBasicRemote().sendText("close");
         Assert.assertEquals("CLOSE", endpoint.message());
         Assert.assertEquals("OPEN", endpoint.message());
+        Assert.assertTrue(session.isOpen()); // Verify session is open before sending the next message
         session.getBasicRemote().sendText("hi");
         Assert.assertEquals("MESSAGE-ECHO-hi", endpoint.message());
         session.getBasicRemote().sendText("close");