No. Even if there were your code would be out of date as soon as you released it. As with most open ended sets of values you should code for the values you know about and ignore everything else. There is no other way to properly handle this situation. New types could be added without notification and you wouldn't want your code to break.
If you care about mailboxes, for example, then run some queries to see what type(s) you are getting back and code for those. If you also want to handle users then do the same thing. Any that you don't recognize you can either ignore or perhaps log a warning somewhere so you can review whether you should be handling them or not.
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