From: Mark Thomas <markt_at_apache.org>
Date: Fri, 9 Oct 2015 22:52:44 +0100

I've been comparing Tomcat's 4.0.0-b01 implementation with the RI and I
found a couple of places where we could simplify things (I'm always in
favour of deleting code if possible).

Both instances are in GenericFilter
- NO-OP destroy() method is unnecessary due to default
  implementation in Filter. Should be removed.
- abstract doFilter() method is unnecessary since
  GenericFilter is abstract. Should be removed.

Mark