Event-Classe:
public class JoinEvent implements Listener {

    @EventHandler
    public void onJoin(PlayerJoinEvent playerJoinEvent) {
        Player player = playerJoinEvent.getPlayer();

        new BuildManager(player).registerPlayer();

        if (Main.getInstance().isBeta()) {
            player.sendMessage("§6§lLobby §7§l│ §8Das LobbySystem befindet sich immoment noch in der §f§lBETA-Phase§8!");
        }
    }
}