Java 16 (and 1.17) is now supported! There are 2 jars now, use the second (newer) only if you are using latest
1.16 or 1.17 with Java 16!
Read the full changelog here.
This update will greatly improve server TPS, this is an example made with a custom stresser in 4 minutes of bots join/leave (plugin with default settings and empty database):