fix(bungee): clear cached bossbars when switching servers

Relates to #439

(cherry picked from commit 03d8945)

Author: diogotcorreia

core/src/main/java/com/rexcantor64/triton/listeners/BungeeListener.java

@@ -17,6 +17,7 @@
 import net.md_5.bungee.event.EventHandler;
 import net.md_5.bungee.event.EventPriority;
 import net.md_5.bungee.netty.PipelineUtils;
+import net.md_5.bungee.protocol.ProtocolConstants;
 
 import java.lang.reflect.Method;
 import java.util.ArrayList;
@@ -33,6 +34,11 @@ public void onPlayerJoin(ServerConnectedEvent event) {
 
         Triton.asBungee().getBridgeManager().sendPlayerLanguage(lp, event.getServer());
 
+        if (event.getPlayer().getPendingConnection().getVersion() >= ProtocolConstants.MINECRAFT_1_20_2) {
+            // On 1.20.2 and above, the join player packet starts clearing bossbars automatically, so clear them here
+            lp.clearCachedBossbars();
+        }
+
         if (Triton.get().getConf().isRunLanguageCommandsOnLogin()) {
             lp.executeCommands(event.getServer());
         }

core/src/main/java/com/rexcantor64/triton/player/BungeeLanguagePlayer.java

@@ -69,6 +69,10 @@ public void removeBossbar(UUID uuid) {
         bossBars.remove(uuid);
     }
 
+    public void clearCachedBossbars() {
+        bossBars.clear();
+    }
+
     public void setLastTabHeader(BaseComponent lastTabHeader) {
         this.lastTabHeader = lastTabHeader.duplicate();
     }