As a result of this discussion, we have created a new wiki page called “DO NOTs”.
Everyone makes mistakes now and then, and you might have noticed that some of those wrong turns you took turned out to be really commonplace. This is the kind of material we’d like you to contribute to this list of all the biggest “bad practices”.
If you’re registered on hub.jmonkeyengine.org then you’re already registered on the wiki. Make sure you’re logged in, point your browser to the DO NOTs page and find the “Wiki” drop-down in the topmost grey navigation bar.
Yes, this is a good thing to have around 
If we add readonly vectors and localized updates we might not have a need for such a page after all.
You will not keep jme2 users from trying to remedy stuff with updateXXX(), so the list should definitely be there. And I see you are intrigued by the idea of readonly math objects… Ok, if you really feel like you must do it… 