I find it mildly irritating that SLF4J Simple logs everything to System.err - it means, for instance, that if you use cargo in Maven to run up Jetty with SLF4J simple then perfectly fine info messages are intercepted and logged as warnings by Maven, purely because they were sent to System.err.

It seems more appropriate to log INFO to System.out and WARN/ERROR to System.err.

Obviously not a big deal, just a minor niggle. Pull request made on github.