I was just talking to someone about Java and they said that it's outdated but afaik it's still a major part of their internal infrastructure. Ofc, they're trying to eat their own dogfood which means they're trying as much as possible to move to AWS for internal services which is basically a mix of customized OSS services programmed in a wide mix of languages, but I imagine mostly C/++ and other low level languages encapsulated in various virtualization solutions.