Need a way to gracefully handle attempts to TASTy-Inspect Java classes

[gzoller]

Today

If I TASTy-inspect a Java class I see a warning on the screen, then nothing happens, which isn't very useful.

(As an aside, I get an alreadyLoaded() warning. I would have expected a cannotUnpickle(s"its class file does not have a TASTY attribute") for a Java class.)

While this behavior is somewhat expected, as there is obviously no .tasty file for Java classes, it would be valuable to know that I encountered a Java file in my top-level TastyInspector implementation, not just "nothing" (empty root tree). As we live on the JVM, I categorize this request as a "friendly-failure", as it could surely happen in the wild.

I seek a way to know if a compilation unit was in fact a Java class from within TastyInspector.

expectation

I'm working on a PR for this, attempting to do as minimal surgery as possible.

My thought is to add a marker class, JavaCompilationUnit, that can be returned from ReadTasty. Then I can add a getJavaClass():Option[String] method on Reflection.Context, which internally will check the CompilationUnit to see if it's a JavaCompilationUnit and return the class name if so. This information I can access from within my TastyInspector and do whatever I need to from there. Those who don't care about Java classes will experience the current behavior minus the warning.