I would tout sealed classes as well, although I think Java has a proposal that's getting traction. For back-end service/API type things in an enterprise settin

I would tout sealed classes as well, although I think Java has a proposal that's getting traction. For back-end service/API type things in an enterprise setting, Kotlin is a good value proposition. There's also probably some truth to the idea that one reason modern Java is adding these things is because of Kotlin's existence.