Fix the player's uuid being null in Bungee mode/offline mode

CraftBukkit-Patches/0055-Fire-PreLogin-Events-in-Offline-Mode.patch

@@ -47,6 +47,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 -            this.g = LoginListener.EnumProtocolState.READY_TO_ACCEPT;
 +            // Spigot start
 +            try {
++                initUUID();
 +                new LoginHandler().fireEvents();
 +            } catch (Exception ex) {
 +                disconnect("Failed to verify username!");