Either you haven't used Java, or didn't look at the examples in the link.

The code looks similar to Java code, how classes are constructed, extra type modifiers, type access levels etc.

Or I'm surprised at the notion that types in an OO language is the minimum bar for "turning into Java"?

That seems like a nonsensical litmus test.

Other languages that have these but they do look different.

I personally don't see anything wrong with it, but it does resemble Java to me.

The OO model is superficially adapted from Java. The open source community is pretty much following the SOLID / clean code cult. There are of course huge differences but the community acts like we're building a second java and there is no scepticism about it.