Go isn't like that, or at least wasn't when G+ was still around.
Nowadays I don't get in touch much with people, but when I create issues Go people are usually not as unfriendly as Java/JVM people.
No idea how you have managed to come to such a conclusion, or what kind of experienced you might have had. I have been part of some of the core JSR/groups, as rather independent/unaffiliated (not oracle/google/hp/ibm/twitter) - there was no gate keeping, elitism or anything alike.
I'd consider mailing lists extremely professional, respectful, even nice.
There are always people like that when groups get big enough.
The thing I love about the JVM ecosystem is the engineering culture. The quality of the platform and most libraries is very high, and well designed.
I don't love the Java language, but it can get the job done.
Maybe it's true for Haskell or Rust. But Java?