Currently, the server runs on Java 8 and some plugins, notably Terrain Control depend on a version-specific hack. Now, we do want to drop TC anyway to upgrade to 1.14.4 but there's also the goal of sharing this plugin for others, who likely run Java 8.
It took me a while to figure out how to make it work with Lombok - have to use the right order.
The command argument processing and permission checking is done asynchronously, mainly because LuckPerms (rightfully) complains that loading player data (for unconnected DC users) should not be done on the main thread.
The actual command execution is still done on the main thread.
