I thought of that. I can often extract MSIs using 7zip. I was about to download until I read that it can only be used for development purposes. Apparently I have to agree not to redistribute it. No thanks Red Hat.

Elsewhere in this thread I discovered:

https://github.com/ojdkbuild/ojdkbuild

And I already knew about:

http://www.azul.com/downloads/zulu/

The more OpenJDK folders I have to test against (on both Linux and Windows), the better. Just change environment variables.