public virtual void OnPendingMigrationTargetChanged(MigrationChangedEventArgs e)
 {
     if (PendingMigrationChanged != null)
     {
         PendingMigrationChanged(this, e);
     }
 }
 public virtual void OnCompletedMigrationChanged(MigrationChangedEventArgs e)
 {
     if (CompletedMigrationChanged != null)
     {
         CompletedMigrationChanged(this, e);
     }
 }