RequestHandlerBase's logger name should point to the implementation class

RequestHandlerBase is an abstract class that defines a private static Logger with a logger name of this very class. I think it should point to the implementing class (getClass()). This would require it be non-static. It's used in just one spot, from a method that isn't static, so this will work.

Do we go farther and declare as protected and remove static loggers in all subclasses, so long as they aren't being referenced from static methods there?

See recent comments at the end of SOLR-8330