public Inventory(ItemsAdapter items, bool specificPrefixes = true) : this(items as IList <ItemData>, specificPrefixes)
 {
     if (items == null)
     {
         throw new ArgumentNullException();
     }
 }
 public Inventory(ItemsAdapter items, bool specificPrefixes = true) : this(items as IList <ItemData>, specificPrefixes)
 {
     //Contract.Requires<ArgumentNullException>(items != null);
     if (items == null)
     {
         throw new ArgumentNullException();
     }
 }