418603 - cannot specify a custom ServerEndpointConfig.Configurator

+ Fixing bad assumption on annotations possibly being null
diff --git a/jetty-websocket/javax-websocket-server-impl/src/main/java/org/eclipse/jetty/websocket/jsr356/server/AnnotatedServerEndpointConfig.java b/jetty-websocket/javax-websocket-server-impl/src/main/java/org/eclipse/jetty/websocket/jsr356/server/AnnotatedServerEndpointConfig.java
index 6846991..4652e9d 100644
--- a/jetty-websocket/javax-websocket-server-impl/src/main/java/org/eclipse/jetty/websocket/jsr356/server/AnnotatedServerEndpointConfig.java
+++ b/jetty-websocket/javax-websocket-server-impl/src/main/java/org/eclipse/jetty/websocket/jsr356/server/AnnotatedServerEndpointConfig.java
@@ -110,7 +110,7 @@
             userProperties.putAll(baseConfig.getUserProperties());
         }
 
-        if (anno.configurator() == null)
+        if (anno.configurator() == ServerEndpointConfig.Configurator.class)
         {
             if (configr != null)
             {