fix itemstack properties in the api

api/src/main/java/lol/pyr/znpcsplus/api/entity/PropertyHolder.java

@@ -1,5 +1,7 @@
 package lol.pyr.znpcsplus.api.entity;
 
+import org.bukkit.inventory.ItemStack;
+
 import java.util.Set;
 
 /**
@@ -32,10 +34,19 @@ public interface PropertyHolder {
      */
     <T> void setProperty(EntityProperty<T> key, T value);
 
+    /**
+     * Weird fix which is sadly required in order to not decrease performance
+     * when using item properties, read https://github.com/Pyrbu/ZNPCsPlus/pull/129#issuecomment-1948777764
+     *
+     * @param key Unique key representing a property
+     * @param value The value to assign to the property key on this holder
+     */
+    void setItemProperty(EntityProperty<?> key, ItemStack value);
+
     /**
      * Method used to get a set of all of the property keys that this holder has a value for
      *
-     * @return List of property keys
+     * @return Set of property keys
      */
     Set<EntityProperty<?>> getAppliedProperties();
 }

plugin/src/main/java/lol/pyr/znpcsplus/entity/PacketEntity.java

@@ -10,6 +10,7 @@ import lol.pyr.znpcsplus.packets.PacketFactory;
 import lol.pyr.znpcsplus.reflection.Reflections;
 import lol.pyr.znpcsplus.util.NpcLocation;
 import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
 
 import java.util.Collection;
 import java.util.Set;
@@ -97,6 +98,11 @@ public class PacketEntity implements PropertyHolder {
         properties.setProperty(key, value);
     }
 
+    @Override
+    public void setItemProperty(EntityProperty<?> key, ItemStack value) {
+        properties.setItemProperty(key, value);
+    }
+
     @Override
     public Set<EntityProperty<?>> getAppliedProperties() {
         return properties.getAppliedProperties();

plugin/src/main/java/lol/pyr/znpcsplus/hologram/HologramLine.java

@@ -7,6 +7,7 @@ import lol.pyr.znpcsplus.entity.PacketEntity;
 import lol.pyr.znpcsplus.packets.PacketFactory;
 import lol.pyr.znpcsplus.util.NpcLocation;
 import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
 
 import java.util.Collection;
 import java.util.HashSet;
@@ -70,6 +71,11 @@ public class HologramLine<M> implements PropertyHolder {
         throw new UnsupportedOperationException("Can't set properties on a hologram line");
     }
 
+    @Override
+    public void setItemProperty(EntityProperty<?> key, ItemStack value) {
+        throw new UnsupportedOperationException("Can't set properties on a hologram line");
+    }
+
     @Override
     public Set<EntityProperty<?>> getAppliedProperties() {
         return properties;

plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcImpl.java

@@ -148,21 +148,26 @@ public class NpcImpl extends Viewable implements Npc {
         return propertyMap.containsKey((EntityPropertyImpl<?>) key);
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     public <T> void setProperty(EntityProperty<T> key, T value) {
-        setProperty((EntityPropertyImpl<T>) key, value);
+        // See https://github.com/Pyrbu/ZNPCsPlus/pull/129#issuecomment-1948777764
+        Object val = value;
+        if (val instanceof ItemStack) val = SpigotConversionUtil.fromBukkitItemStack((ItemStack) val);
+
+        setProperty((EntityPropertyImpl<T>) key, (T) val);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void setItemProperty(EntityProperty<?> key, ItemStack value) {
+        setProperty((EntityPropertyImpl<com.github.retrooper.packetevents.protocol.item.ItemStack>) key, SpigotConversionUtil.fromBukkitItemStack(value));
     }
 
     public <T> void setProperty(EntityPropertyImpl<T> key, T value) {
         if (key == null) return;
         if (value == null || value.equals(key.getDefaultValue())) propertyMap.remove(key);
-        if (value instanceof ItemStack) {
+        else propertyMap.put(key, value);
-            ItemStack item = (ItemStack) value;
-            com.github.retrooper.packetevents.protocol.item.ItemStack packetItem = SpigotConversionUtil.fromBukkitItemStack(item);
-            propertyMap.put(key, packetItem);
-        } else {
-            propertyMap.put(key, value);
-        }
         UNSAFE_refreshProperty(key);
     }