From ab304a096e9f361b8b920540bbcd805d7443be2b Mon Sep 17 00:00:00 2001
From: lachan-roberts <lachlan@webtide.com>
Date: Wed, 6 Mar 2019 17:11:57 +1100
Subject: [PATCH] avoid adding NULL UpgradeListeners to WebSocketClient

Signed-off-by: lachan-roberts <lachlan@webtide.com>
---
 .../org/eclipse/jetty/websocket/client/WebSocketClient.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/jetty-websocket/jetty-websocket-client/src/main/java/org/eclipse/jetty/websocket/client/WebSocketClient.java b/jetty-websocket/jetty-websocket-client/src/main/java/org/eclipse/jetty/websocket/client/WebSocketClient.java
index 78f5e77d98d..00ecfb1fede 100644
--- a/jetty-websocket/jetty-websocket-client/src/main/java/org/eclipse/jetty/websocket/client/WebSocketClient.java
+++ b/jetty-websocket/jetty-websocket-client/src/main/java/org/eclipse/jetty/websocket/client/WebSocketClient.java
@@ -135,7 +135,8 @@ public class WebSocketClient extends ContainerLifeCycle implements WebSocketPoli
     public CompletableFuture<Session> connect(Object websocket, URI toUri, UpgradeRequest request, UpgradeListener listener) throws IOException
     {
         JettyClientUpgradeRequest upgradeRequest = new JettyClientUpgradeRequest(this, coreClient, request, toUri, websocket);
-        upgradeRequest.addListener(listener);
+        if (listener != null)
+            upgradeRequest.addListener(listener);
         coreClient.connect(upgradeRequest);
         return upgradeRequest.getFutureSession();
     }