The SpotBugs codebase includes examples of:

• JDK 1.4+ built-in logging, eg in edu.umd.cs.findbugs.FindBugs and edu.umd.cs.findbugs.gui2.MainFrameComponentFactory
• Multiple incompatible hand-rolled logging setups, based on edu.umd.cs.findbugs.classfile.IErrorLogger and edu.umd.cs.findbugs.log.Logger
• STDOUT/STDERR logging, all over the place. Note that @spotbugs-bot marks this as a major defect.

We should choose a preferred logging style and stick to it.