fixed arena transfer with empty inventory slots and blocked advancements in the arena

arena/src/main/java/eu/mhsl/craftattack/spawn/arena/appliances/arena/Arena.java

@@ -373,6 +373,7 @@ public class Arena extends Appliance {
             new FightListener(),
             new WorldProtectionListener(),
             new ModeMenuListener(),
+            new NoProgressListener(),
             new PlayerInteractAtEntityEventListener(villager, event -> this.sendToCraftAttack(event.getPlayer())),
             new DismissInventoryOpenFromHolder(villager)
         );

arena/src/main/java/eu/mhsl/craftattack/spawn/arena/appliances/arena/ArenaWorlds.java

@@ -39,6 +39,7 @@ final class ArenaWorlds {
             world.setGameRule(GameRules.SPAWN_WARDENS, false);
             world.setGameRule(GameRules.RAIDS, false);
             world.setGameRule(GameRules.SHOW_DEATH_MESSAGES, false);
+            world.setGameRule(GameRules.SHOW_ADVANCEMENT_MESSAGES, false);
             world.setStorm(false);
             world.setThundering(false);
             world.setTime(6000);

arena/src/main/java/eu/mhsl/craftattack/spawn/arena/appliances/arena/NoProgressListener.java

@@ -0,0 +1,21 @@
+package eu.mhsl.craftattack.spawn.arena.appliances.arena;
+
+import com.destroystokyo.paper.event.player.PlayerAdvancementCriterionGrantEvent;
+import eu.mhsl.craftattack.spawn.core.appliance.ApplianceListener;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.player.PlayerRecipeDiscoverEvent;
+
+/**
+ * Nothing done in the arena counts as progress: no advancements, no recipe unlocks.
+ */
+class NoProgressListener extends ApplianceListener<Arena> {
+    @EventHandler
+    public void onCriterion(PlayerAdvancementCriterionGrantEvent event) {
+        event.setCancelled(true);
+    }
+
+    @EventHandler
+    public void onRecipe(PlayerRecipeDiscoverEvent event) {
+        event.setCancelled(true);
+    }
+}

craftattack/src/main/java/eu/mhsl/craftattack/spawn/craftattack/appliances/metaGameplay/arenaPortal/ArenaPortal.java

@@ -20,7 +20,6 @@ import org.bukkit.event.Listener;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.ArrayList;
 import java.util.Base64;
 import java.util.HashSet;
 import java.util.List;
@@ -75,8 +74,7 @@ public class ArenaPortal extends Appliance {
         if(!this.pendingTransfers.add(player.getUniqueId())) return;
         player.sendActionBar(Component.text("Du wirst zur Arena gebracht...", NamedTextColor.GRAY));
 
-        List<ItemStack> contents = new ArrayList<>(List.of(player.getInventory().getContents()));
-        String items = Base64.getEncoder().encodeToString(ItemStack.serializeItemsAsBytes(contents));
+        String items = Base64.getEncoder().encodeToString(ItemStack.serializeItemsAsBytes(player.getInventory().getContents()));
         ArenaRepository.InventorySnapshot snapshot = new ArenaRepository.InventorySnapshot(player.getUniqueId(), items);
 
         Bukkit.getScheduler().runTaskAsynchronously(Main.instance(), () -> {