Include exception in failed delivery log

src/net/java/sip/communicator/impl/netaddr/NetworkEventDispatcher.java

@@ -133,7 +133,8 @@ static void fireChangeEvent(ChangeEvent evt,
             listener.configurationChanged(evt);
         } catch (Throwable e)
         {
-            logger.warn("Error delivering event:" + evt + ", to:" + listener);
+            logger
+                .warn("Error delivering event:" + evt + ", to:" + listener, e);
         }
     }