make world identifier valid by hex encoding them

SpigotCore/SpigotCore_Main/src/de/steamwar/core/WorldIdentifier.java

@@ -27,6 +27,9 @@ import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.level.Level;
 
+import java.nio.charset.StandardCharsets;
+import java.util.HexFormat;
+
 @Linked
 public class WorldIdentifier {
 
@@ -36,6 +39,10 @@ public class WorldIdentifier {
         resourceKey = new ResourceKey<>(new ResourceLocation("minecraft", "dimension"), new ResourceLocation("steamwar", name));
     }
 
+    public static void setArena(String map) {
+        set("arena/" + Core.getVersion() + "/" + HexFormat.of().formatHex(map.getBytes(StandardCharsets.UTF_8)));
+    }
+
     public WorldIdentifier() {
         TinyProtocol.instance.addFilter(ClientboundLoginPacket.class, (player, packet) -> {
             if (resourceKey == null) return packet;