"people working actively in "modern" Go codebases with generics, is it becoming like a Java/Spring kind of codebase?"

I have yet to encounter a 3rd party library that uses generics that isn't a data structure library of some sort. The only person I have seen doing crazy things with generics is... me. In my own code, for the most part [1]. In general I don't even see generics that are so much as parameterized by a meaningful interface like "type BlahBlah[R io.Reader]"; generics are so often parameterized by "any" that a casual reader might be forgiven for thinking that that is all a Go generic can do. As is often the case, the most complicated generic type signatures are the one in the standard library and even they aren't really all that bad, it's really just about the "~" operator allowing support for "all types that are either 'string' or something of the form 'type X string'".

I see the occasional person complain about how generics have ruined Go by making them too complicated. I push back on them with basically the previous paragraph. None of them have ever replied to press their point any farther. I interpret this to mean that their experience with the feature is in fact the same. At this point if you're buried in super complicated generics it is almost certainly someone on your own team and you should tell them to stop.

Similarly for iterators, by the way. The way Go did iterators is a bit odd to implement them yourself. Won't deny that. But it does compile down very efficiently, and only matters to the people writing the iterator not the consumer. Anyone who claims it has wrecked the language is invited to explain to me why it is that they are writing so many dozens of iterators all the time first, because as near as I can tell they aren't getting that from 3rd party libraries or the standard library.

[1]: The exception being https://github.com/thejerf/mtmap if you want to see something that I did find a use for, and you may have a use for, but is not something I would suggest using all the time. Very specific use case I had.