Events/FMLCommonSetupEvent/1.16

This event is a parallel dispatch event - you must use event.enqueueWork to interact with the game state in any way.

CommonSetup is fired after all the Events/RegistryEvent/1.16s, but before the Events/FMLClientSetupEvent/1.16 and Events/FMLDedicatedServerSetupEvent/1.16. This makes it useful for non-specific mod setup.

Register it any way you would normally register an event.