/// <summary>
/// Initializes a new instance of the ImportConsumerBase class
/// </summary>
/// <param name="source">the importsource that is providing data for this consumer</param>
/// <param name="virtualColumns">a set of columns that is evaluated on does not directly result from the provided Data</param>
protected ImportConsumerBase(IImportSource <T, TNotification> source, ConstConfigurationCollection virtualColumns)
{
VirtualColumns = virtualColumns;
AcceptanceConstraints = new SimpleDecider <T>(false);
this.source = source;
source.Register(this);
}
