SOLR-17485 Remove CheckLoggingConfiguration; unnecessary
Also note we extend HttpFilter instead of ServletFilter.
https://issues.apache.org/jira/browse/SOLR-17485
Addressing your nit on renaming _request to request wasn't fully possible for various reasons at first, so I started pulling on that thread, doing some refactoring that ultimately led to me doing that rename. CC @gus-asf for review on my changes (commit messages explain what I did too). Happy to decouple such changes to another PR; it's out of scope.
Granted the scope has been somewhat flexible, maybe too much... this started with me wondering, why can't we just use HttpServletRequest instead of the old ServletRequest. Oh hey look, we have some old base class that isn't what I expect, doing some old logging stuff that's obsolete / useless (IMO). So let's just subclass HttpFilter.
An aside, the excludedPath thing seems bolted on and shouldn't have been added.
Naming looks great, and some simplifications. I tried to understand from javadocs what excludedPath was all about and didn't grok it but that isn't important.