/// <summary>
 /// Add item.to <see cref="Items"/>
 /// </summary>
 /// <param name="item">
 /// The item.
 /// </param>
 protected void AddInternalItem(IItemMap item)
 {
     this._items.Add(item);
 }
 /// <summary>
 /// Initializes a new instance of the <see cref="ItemMapMutableCore"/> class.
 /// </summary>
 /// <param name="itemMap">
 /// The itemMap. 
 /// </param>
 public ItemMapMutableCore(IItemMap itemMap)
     : base(itemMap)
 {
     this.SourceId = itemMap.SourceId;
     this.TargetId = itemMap.TargetId;
 }