Synchronize access to skins map in PlayerSkinHandler to ensure thread safety and prevent race conditions.

VelocityCore/src/de/steamwar/velocitycore/network/handlers/PlayerSkinHandler.java

@@ -54,7 +54,7 @@ public class PlayerSkinHandler extends PacketHandler {
         VelocityCore.getProxy().getEventManager().register(VelocityCore.get(), this);
     }
 
-    private Map<UUID, SkinData> skins = new LinkedHashMap<>(maxCacheSize, 1, true) {
+    private final Map<UUID, SkinData> skins = new LinkedHashMap<>(maxCacheSize, 1, true) {
         @Override
         protected boolean removeEldestEntry(Map.Entry<UUID, SkinData> eldest) {
             return size() > maxCacheSize;
@@ -64,6 +64,7 @@ public class PlayerSkinHandler extends PacketHandler {
     @Handler
     @SneakyThrows
     public void handle(PlayerSkinRequestPacket packet) {
+        synchronized (skins) {
             if (skins.containsKey(packet.getUuid())) {
                 SkinData skinData = skins.get(packet.getUuid());
                 NetworkSender.send(((ServerMetaInfo) packet.getMetaInfos()).sender().getServer(), new PlayerSkinResponsePacket(packet.getUuid(), skinData.skin, skinData.signature));
@@ -98,6 +99,7 @@ public class PlayerSkinHandler extends PacketHandler {
                 }
             }
         }
+    }
 
     @Subscribe
     public void onPostLogin(PostLoginEvent event) {
@@ -105,6 +107,8 @@ public class PlayerSkinHandler extends PacketHandler {
         GameProfile gameProfile = player.getGameProfile();
         GameProfile.Property property = gameProfile.getProperties().stream().filter(p -> p.getName().equals("textures")).findFirst().orElse(null);
         if (property == null) return;
+
+        synchronized (skins) {
             skins.put(player.getUniqueId(), new SkinData(property.getValue(), property.getSignature()));
 
             Set<UUID> uuidSet = skins.keySet();
@@ -114,6 +118,7 @@ public class PlayerSkinHandler extends PacketHandler {
                 }
             });
         }
+    }
 
     public record SkinData(String skin, String signature) {}
 }