We use Java containers in production on a very large scale system. We are actively migrating stuff away from Java to Go, because the JVM is a nightmare in containers. Sure we could make do and configure the JVM to hell and hack things to get it to work...but why bother? We have to allocate hundreds of MB of memory for a simple HTTP server. The tons of configuration and hacks are maintenance nightmares. It's been a terrible experience all around. Java is bloated, it's a resource hog, and the ecosystem doesn't care about cold start times. It's just a terrible fit for a containerized environment.