/// <summary>
/// Adds a new operation warning notification.
/// </summary>
/// <param name="code">Notification code</param>
/// <param name="attributes">Optional notification attributes</param>
/// <param name="exception">Optional notification exception</param>
/// <returns>This exception object</returns>
/// <remarks>
/// This method can be used directly in throw statement.
/// </remarks>
public BusinessOperationException AddOperationWarning(string code,
IList <object> attributes = null, Exception exception = null)
{
EnsureNotifications();
Notifications.AddOperationWarning(code, attributes, exception);
return(this);
}