RequestFilter - Improve Error Information on Servlet Exception

The notorious ServletException does not give you any helpful information as to what is really the problem.

The catch statement in RequestFilter.doFilter() only logs the generic Throwable, so if this is a ServletException, you get no real helpful information as to what the problem might be.

I have written a small snippet of code to check if the Throwable is a ServletException and if so, to log the root cause of the Exception in an effort to assist the developer in tracking down the actual problem (patch attached).

Can this be added to the 2.4.x branch and current 2.5 and 2.6 versions (if not already)?