I think there is plenty of evidence that you don't need to touch java the language now. However, if you need to interop with existing libraries or between lang

I think there is plenty of evidence that you don't need to touch java the language now. However, if you need to interop with existing libraries or between languages (not specifically java language) then it is probably worthwhile at least understanding how interfaces work in java (and most languages would allow you to define them in their own language) - as that is often used at the edges of systems (and its also pretty simple).