It doesn't exist in Go either. https://go.dev/ref/spec

That's why you find it in the comments. That is where tools have found a place to add their own syntax without breaking the Go code.

Absolutely you can do the same in Java. It exists to the exact same degree as it does in Go. I expect it isn't done as often in the Java world because it is much harder to parse Java code so the tools don't get built.