[agentgt]

The problem is that it is a Facade/API that is initializing and printing to STDERR.

I completely disagree with the idea of making slf4j-nop a required exclusion dependency (that is a I agree with @paulmd and not the OP) but a facade/api should have very little interaction with the boot process of Java. The default should be to do nothing and require either a java.util.ServiceLoader like mechanism or some other explicit configuration (or in SL4J's case adding a bridge).

That is slf4j-nop behavior should be the default (not the dependency). I understand that would confuse users but I think it would be the correct behavior. (also see my other comment for more reasons)