Fix gift boxes not giving gifts when being bought from the shop

src/main/java/emu/nebula/data/resources/DropPkgDef.java

@@ -0,0 +1,40 @@
+package emu.nebula.data.resources;
+
+import emu.nebula.data.BaseDef;
+import emu.nebula.data.ResourceType;
+import emu.nebula.util.Utils;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
+import lombok.Getter;
+
+@Getter
+@ResourceType(name = "DropPkg.json")
+public class DropPkgDef extends BaseDef {
+    private int PkgId;
+    private int ItemId;
+    
+    private static Int2ObjectMap<IntList> PACKAGES = new Int2ObjectOpenHashMap<>();
+    
+    @Override
+    public int getId() {
+        return PkgId;
+    }
+    
+    @Override
+    public void onLoad() {
+        var packageList = PACKAGES.computeIfAbsent(this.PkgId, i -> new IntArrayList());
+        packageList.add(this.ItemId);
+    }
+    
+    public static int getRandomDrop(int packageId) {
+        var packageList = PACKAGES.get(packageId);
+        
+        if (packageList == null) {
+            return 0;
+        }
+        
+        return Utils.randomElement(packageList);
+    }
+}