Always replace spaces in usernames when using Floodgate

Bungeecord recently started checking usernames for spaces in the login start packet. To resolve this we just always send the username without spaces in the login start packet. Floodgate is still able to get the real username of the Bedrock player and Floodgate is also still in charge of the final username.

connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java

@@ -581,7 +581,14 @@ public class GeyserSession implements CommandSender {
 
                     protocol = new MinecraftProtocol(authenticationService.getSelectedProfile(), authenticationService.getAccessToken());
                 } else {
-                    protocol = new MinecraftProtocol(username);
+                    // always replace spaces when using Floodgate,
+                    // as usernames with spaces cause issues with Bungeecord's login cycle
+                    String validUsername = username;
+                    if (remoteAuthType == AuthType.FLOODGATE) {
+                        validUsername = username.replace(' ', '_');
+                    }
+
+                    protocol = new MinecraftProtocol(validUsername);
                 }
 
                 connectDownstream();