Add: ILuaUserData.UserValues property

src/Lua/LuaUserData.cs

@@ -1,6 +1,22 @@
 namespace Lua;
 
+internal sealed class LuaUserData : ILuaUserData
+{
+    public LuaTable? Metatable { get; set; }
+    readonly LuaValue[] userValues = new LuaValue[1];
+    public Span<LuaValue> UserValues => userValues;
+
+    public LuaUserData(LuaValue value, LuaTable? metatable)
+    {
+        userValues[0] = value;
+        Metatable = metatable;
+    }
+}
+
 public interface ILuaUserData
 {
     LuaTable? Metatable { get; set; }
+
+    //We use span for compatibility with lua5.4.
+    Span<LuaValue> UserValues => default;
 }