[shakna]

At a guess, may be useful when:

* Working with old enterprise libraries ("just use the jar!")

* Optimisation when dealing with a compile to JVM language like Closure or Scala

* Research, such as reverse engineering badly behaved jars.

[haggy]

Not really sure why this would be helpful only with Scala in this case. Scala is not transpiled, it's compiled directly to bytecode just like Java so if it was helpful with Scala it should be helpful with Java as well.