[WorldMaker]

Given the description also describes moving from a custom event sourcing engine to Kafka it doesn't seem to be moving away from reactive programming. As much as anything it seems like something of an "Apache Effect" that some Enterprise Highly Paid Consultants came in, told them they were doing "everything wrong" and that everything would be better with off the shelf open source components and that the "best" language for working with off the shelf open source components is Java. Most of that isn't true in various ways, but the number of Enterprise HPCs that love Java despite that language's deficiencies is surprisingly high. (Though maybe not that surprising given Oracle owns Java today and has always directly and indirectly owned a lot of HPCs in the Enterprise space.)

[bunderbunder]

There's a very strong "nobody ever got fired for choosing IBM" effect surrounding Java. I can list specific situations where I'd prefer another platform all day long. But there are only a few specific situations I can think of where I would say Java is not a defensible choice.

And giving advice that's optimally defensible is the Highly Paid Consultant's actual job. You don't bring a consultant like that in when you're playing to win; you do it when you're playing to not lose.