Java defines it in a very useful way. It's identical to an AtomicReference, but without any test&set semantics. Anything other than that seems pretty dangerous.

Personally I find the issue with volatile is that it's quite subtle unless you're looking at the declaration. I tend to use AtomicReference even if I don't need test&set, unless it's extremely performance critical, but it almost never is. The inner loop variables don't need to be volatile.