I had a meeting at work recently where a small debate was brought up as to what sorts of things to log at each logging level. I had my own opinion about it, of course, but I noticed that there are brief notes in the javadocs about each level (going back in the git logs, it look like Ralph wrote those notes almost 6 years ago!) and that's about it when it comes to any sort of specifics.
Does anyone have some more elaborations on why you'd use each level? Or some more concrete differences between, for example, error/warn and debug/trace? Perhaps some examples reflecting how you've used it in the past or even custom logging levels you've added?
In a related idea, I'm kind of thinking that a general page about logging concepts may be useful for the manual, so I'd like to gather some opinions on said topics first.