Google's major Go projects appear to be gVisor, Android GPGPU debugger, Fucshia's TCP/IP stack and volume management tools and the download server as it was done by the Go team.
https://commandcenter.blogspot.com/2012/06/less-is-exponenti...
"In this talk we explore the devastating effects using object oriented antipatterns in go while building programs in a monorepo. ... Unknown to most, Kubernetes was originally written in Java. If you have ever looked at the source code, or vendored a library you probably have already noticed a fair amount of factory patterns and singletons littered throughout the code base. "
So basically writing Java in Go lead to clusterfuck codebase.
Most of the codebase problems in Kube are:
1. we depended on half the Go ecosystem at one point (docker, grpc, etcd, a few others) which is hard to do with dependencies in go (few standardized libraries)
2. performance of serialization mattered and JSON and protobuf were still raw at the time
I don't think Kubernetes is any worse than any other large (3M+ LOC), relatively young codebase I've seen on average.