[groestl]

> we still have to keep them chugging along on Java 8

There's something else amiss here. Compared to other platforms, upgrading Java, even on complex codebases, has never been a nightmare for me.

[chopin]

The problem in a large codebase is keeping consistency when upgrading.

I upgraded a codebase of approx 100 kloc from Java 7 to Java 8 a couple of years ago. As I didn't want mixed patterns for the same thing throughout the code base I replaced most of the loops with their streaming equivalent. I had the luxury of having the budget for doing so.

Mixing patterns of newer language features alongside older ones can make the code base hard to read.