public static void PopulateIdentifier(Entity booking, BookingIdentifier identifier, ITracingService trace)
 {
     if (trace == null)
     {
         throw new InvalidPluginExecutionException("Tracing service is null;");
     }
     trace.Trace("Booking Identifier - start");
     if (booking == null)
     {
         throw new InvalidPluginExecutionException("Booking entity is null.");
     }
     if (identifier == null)
     {
         throw new InvalidPluginExecutionException("Booking identifier is null.");
     }
     if (identifier != null)
     {
         trace.Trace("Booking populate identifier - start");
         booking[Attributes.Booking.Name]                    = identifier.BookingNumber;
         booking[Attributes.Booking.OnTourVersion]           = (identifier.BookingVersionOnTour != null) ? identifier.BookingVersionOnTour : string.Empty;
         booking[Attributes.Booking.TourOperatorVersion]     = (identifier.BookingVersionTourOperator != null) ? identifier.BookingVersionTourOperator : string.Empty;
         booking[Attributes.Booking.OnTourUpdatedDate]       = !string.IsNullOrWhiteSpace(identifier.BookingUpdateDateOnTour) ? Convert.ToDateTime(identifier.BookingUpdateDateOnTour) : (DateTime?)null;
         booking[Attributes.Booking.TourOperatorUpdatedDate] = !string.IsNullOrWhiteSpace(identifier.BookingUpdateDateTourOperator) ? Convert.ToDateTime(identifier.BookingUpdateDateTourOperator) : (DateTime?)null;
         booking[Attributes.Booking.SourceApplication]       = identifier.SourceApplication != SourceApplication.NotSpecified ? identifier.SourceApplication.ToString() : null;
         booking[Attributes.Booking.SourceSystem]            = identifier.BookingSystem.ToString();
         booking[Attributes.Booking.DealSequenceNumber]      = identifier.DealSequenceNumber;
         booking[Attributes.Booking.ConsultationReferenceId] = (!string.IsNullOrWhiteSpace(identifier.ConsultationReference)) ?
                                                               new EntityReference(EntityName.TravelPlanner,
                                                                                   new Guid(identifier.ConsultationReference)) : null;
         booking[Attributes.Booking.SourceSystemId] = CommonXrm.GetSourceSystem(identifier.SourceSystem);
         trace.Trace("Booking populate identifier - end");
     }
     trace.Trace("Booking Identifier - end");
 }