WindowsDesktopSSOConfig ClassCastException on saving configuration in admin UI

When saving the WindowsDesktopSSO configuration of a realm in the admin UI a ClassCastException is logged in the Configuration debug log.

This only seems to happen when multiple servers are configured, a single standalone server does not show the error.

amSMSEvent:03/05/2012 05:09:13:260 AM EST: Thread[smIdmThreadPool,5,main]
ERROR: ServiceConfigManagerImpl(:iPlanetAMAuthWindowsDesktopSSOService) notifyOrgConfigChange Error sending notification to ServiceListener: com.sun.identity.authentication.config.AMAuthLevelManager
java.lang.ClassCastException: com.sun.identity.authentication.modules.windowsdesktopsso.WindowsDesktopSSOConfig cannot be cast to com.sun.identity.authentication.config.AMConfiguration
at com.sun.identity.authentication.config.AMAuthLevelManager.processAuthConfigEntry(AMAuthLevelManager.java:681)
at com.sun.identity.authentication.config.AMAuthLevelManager.updateAuthConfiguration(AMAuthLevelManager.java:578)
at com.sun.identity.authentication.config.AMAuthLevelManager.organizationConfigChanged(AMAuthLevelManager.java:443)
at com.sun.identity.sm.ServiceConfigManagerImpl.notifyOrgConfigChange(ServiceConfigManagerImpl.java:489)
at com.sun.identity.sm.ServiceConfigManagerImpl.objectChanged(ServiceConfigManagerImpl.java:449)
at com.sun.identity.sm.SMSNotificationManager.sendNotifications(SMSNotificationManager.java:289)
at com.sun.identity.sm.SMSNotificationManager$LocalChangeNotifcationTask.run(SMSNotificationManager.java:365)
at com.iplanet.am.util.ThreadPool$WorkerThread.run(ThreadPool.java:306)

The WindowsDesktopSSOConfig inherits from javax.security.auth.login.Configuration instead of AMConfig so that is obviously the reason for the error message. However, I'm not sure if the inheritance is wrong of if the AMAuthLevelManager.processAuthConfigEntry() is trying to do something odd.

The error goes away when modifying WindowsDesktopSSOConfig as follows:

--- WindowsDesktopSSOConfig.java.orig   Tue Feb  7 07:52:22 2012
+++ WindowsDesktopSSOConfig.java        Fri Mar  2 08:32:39 2012
@@ -35,8 +35,9 @@

 import com.iplanet.am.util.SystemProperties;
 import com.sun.identity.shared.Constants;
+import com.sun.identity.authentication.config.AMConfiguration;

-public class WindowsDesktopSSOConfig extends Configuration {
+public class WindowsDesktopSSOConfig extends AMConfiguration {
     public static final String defaultAppName =
         "com.sun.identity.authentication.windowsdesktopsso";
     private static final String kerberosModuleName =
@@ -56,6 +57,7 @@
      * @param config
      */
     public WindowsDesktopSSOConfig(Configuration config) {
+        super(config);
         this.config = config;
     }