I’ve definitely run into the Malformed class name error while self-employing myself at my day job of writing an obfuscator for the JVM. There are so many edge cases, it’s crazy.

Along the lines of the malformed class name error, is a similar restriction around resource names. I found out the hard way recently that findResource won’t find resources named, say, bundle.js.map. This is because bundle.js.map does not follow the format of name.extension that is expected. The crazy bit is that you can still get at those resource files (they do end up in the JAR), just not with the conventional methods.