Go generics already shipped. I wasn't around for Java 4 days so I don't really know when the main operations shipped but one language maintainer was categorically against it so I wouldn't hold high hopes.

Go generics are still in their infancy. Java generics enabled a lot of functionality that came later. But java generics and particularly type erasure are nothing to write home about, and Go maintainers were also said to be against them, so who knows if comprehensions or other features might pop up one day.