public ItemEvent(Guid listId, Guid itemId, ShoppingEventType type) : base(type, listId) { ItemId = itemId; }
public ShoppingUserEvent(ShoppingEventType type, Guid userId) : base(type) { UserId = userId; }
public ShoppingListEvent(ShoppingEventType type, Guid listId) : base(type) { ListId = listId; }
public ShoppingEvent(ShoppingEventType type) { Type = type; }