ClientSessionEndListener not working

I'm trying to capture the moment when a vSphere client session ends so I can perform some cleanup on my services, but my sessionEnded method is still not being called when I log out of vSphere.

I found the related thread that suggests looking at the vsphere views sample for an example. 

I implemented the ClientSessionEndListener interface on one of my service beans, added method sessionEnded, and passed in the UserSessionService to the same bean in bundle-context.xml.  However, sessionEnded is still not getting called. 

What might I be missing?

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