Patrick Kua gets it
I just read Patrick Kua's excellent blog about how to setup Checkstyle with a custom Check to ensure that sessions are properly closed within method scopes. It really nice when somebody you have never met, gets how to use Checkstyle properly.
On my current project, one person wrote a custom Check to ensure that all caught exceptions were either were properly logged or were wrapped and re-thrown. This helped address the problem where we were losing valuable debugging information.