jars-cache entries not cleared after plugin removal

I was removing and reinstalling QuickNotepad unti I was blue in the face.
No matter how many times I did it, I still saw version 4.4 instead of 5.0 in the manage panel.

Finally, I removed jars-cache, and then I was able to see version 5.0 in plugin manager.

I think removing a plugin (deleting it from plugin manager) should remove all of the plugin's related data from jars-cache.