/// <summary>
/// Determines whether [contains] [the specified item].
/// </summary>
/// <param name="item">The item.</param>
/// <returns>
/// <c>true</c> if [contains] [the specified item]; otherwise, <c>false</c>.
/// </returns>
public bool Contains(TEntity item)
{
if (item == null)
{
return(false);
}
return(_tracker.Any(pair => pair.Key == item.Id));
}