add user properties methods support items

src/content/loading/ItemLoader.cpp

@@ -1,5 +1,6 @@
 #define VC_ENABLE_REFLECTION
 #include "ContentUnitLoader.hpp"
+#include "ContentLoadingCommons.hpp"
 
 #include "../ContentBuilder.hpp"
 #include "coders/json.hpp"
@@ -12,11 +13,12 @@
 
 static debug::Logger logger("item-content-loader");
 
+
 template<> void ContentUnitLoader<ItemDef>::loadUnit(
     ItemDef& def, const std::string& name, const io::path& file
 ) {
     auto root = io::read_json(file);
-    def.properties = root;
+    process_properties(def, name, root);
 
     if (root.has("parent")) {
         const auto& parentName = root["parent"].asString();