Ok, now before you pass this thread. THIS IS THE ACTUAL ONE, by this I mean. I removed all the API, and everything that makes AGC NOT WORK, All you need for this to work. Is ProtocolLib, and it will work. Trust me, drop it in your plugins folder start your server, you're done.
I just tried this and sorry it does not work as a plugin for me. Also, this is the very old 2017 leak and does not provide any new source. Also, the link for download is not working at all anymore