VanillaCord downloads and patches a vanilla Minecraft server, so proxies can connect to it with your choice of BungeeCord, BungeeGuard, or Velocity IP forwarding enabled.
java -jar VanillaCord.jar <versions...>
For Minecraft 1.7, 1.8, 1.9, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, snapshots, and pre-releases
https://dev.me1312.net/jenkins/job/VanillaCord