Github user bitstorm commented on the issue:
https://github.com/apache/wicket/pull/233
I'm fine with this quick fix, but I warmly suggest to improve it after it
has been applied, at least in master branch.
About concurrent access afaik we do have to take care of concurrency. At
the moment we don't have any guarantee that setSessionAttribute saves the entry
for the last request submitted (for the same session). ---
