Glassfish Java App Class cast exception

Getting the following exception when casting

fqe.dataHandler.LiveUpdateMessage cannot be cast to fqe.dataHandler.LiveUpdateMessage

Sometimes it happ开发者_高级运维ens, sometimes it doesn't. The object can never be anything other than that class.

If it helps this is when getting the Object from grizzly-comet's CometEvent.message() function on GlassFish 3.

Thanks in advance for any help.

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This is usually due in a Servlet Engine when you have two instances of a jar file being loaded by different ClassLoaders. Maybe one in a WAR and another in the classpath of the engine ?