I'm noticing an issue with using the conversion characters which generate caller class information. In a project I'm working on, logging is done via a sort of Monitor framework. Anything can back the Monitor whether it be System.out, nothing, Log4j, etc. This makes it so that no logging framework becomes a runtime dependency of the library unless a user explicitly configures the library to use a particular Monitor implementation such as one backed by Log4j. The thing is, classes call the monitor to let the obfuscated logger implementation do the logging. As such, if I use the Log4j implementation and use the conversion characters such as "C", "F", "L", and "M", it ends up looking like logging came from the Log4jMonitor rather than the class that is calling the log4j monitor, which is what I'd want.

The whole Monitor idea kind of came from this post: http://paulhammant.com/blog//000241.html