Floodgate
Hybrid mode plugin to allow for connections from Geyser to join online mode servers.
Geyser is an open collaboration project by CubeCraft Games.
See the Floodgate section in the GeyserMC Wiki for more info about what Floodgate is, how you setup Floodgate and known issues/caveats. Additionally, it includes a more in-depth look into how Floodgate works and the Floodgate API.