webwork bug causes obscure errors

there is a bug in the webwork tag handler code that causes occassional and very obscure errors. the errors are probably dependent on the container in use, and how they handle request and pageContext objects.

in particular, WebWorkTagSupport (and possibly WebWorkBodyTagSupport) try to cache a ValueStack insatnce, as in

protected ServletValueStack getStack()

{ if(stack == null) stack = ServletValueStack.getStack(super.pageContext); return stack; }

the problem (I think) is that the cached ValueSatck may have the wrong pageContext. the context may have been released or even reused.

this bug might manifest itself in various ways. for me, I started getting exceptions in processing a certain webwork expression. in fact, it was very similar to JRA-2471.
I suspect that underlying bug in that issue is the same as in mine.

my solution, for now, is to removing the caching, and instead always call getStack(pageContext). after making this change, the eror disappears and everything works fine.