Incorrect handling of timestamps in clustered session

ClusteredSession has an "outdatedTime" field that records the timestamp when a session gets a callback notifying of a modification on another node. If the session state later gets updated from the distributed cache, the clearOutdated() method ends up setting the session timestamp to that "outdatedTime" rather than the correct timestamp that's stored in the distributed cache. That's wrong.

Not a big deal, as the difference between the outdatedTime and the correct timestamp is probably just a few ms (time it takes to replicate the session). But still, it's wrong.

In any case the handling of "outdatedTime" is more complex than need and related "outdatedVersion" field can be removed altogether. There's a bit of cruft here from the old days when correct timestamps weren't readily available from the cache.