until released open-source, it is vaporware.
It has been open source the whole time. The ongoing work can be tracked on github.
sorry, i didn't realize it was in the master already.
It's not in master, I'm working on it with tewinget. Unfortunately, because of the way the code was originally written, it requires a massive refactor of the consensus code for block acceptance/storage/reorganization and so is going to take a little while.
https://github.com/tewinget/bitmonero/tree/blockchain