/// <summary>
 /// Registers the addition of one or more entities.
 /// </summary>
 /// <param name="entities">The list of entities.</param>
 public void Add(IEnumerable <TEntity> entities) => _changes.AddRange(DbSetChange.Add(entities));
 /// <summary>
 /// Registers the addition of a new entity.
 /// </summary>
 /// <param name="entity">The new entity.</param>
 public void Add(TEntity entity) => _changes.Add(DbSetChange.Add(entity));