public ParcelEditToken ShrinkParcelsToSeeds( 
   ParcelLayer parcelLayer,
   SelectionSet sourceFeatures
)

string errorMessage = await QueuedTask.Run(async () =>
{
  var myParcelFabricLayer = MapView.Active.Map.GetLayersAsFlattenedList().OfType<ParcelLayer>().FirstOrDefault();
  if (myParcelFabricLayer == null)
    return "Please add a parcel fabric to the map";
  try
  {
    FeatureLayer parcelPolygonLyr = null;
    //find the first layer that is a polygon parcel type, is non-historic, and has a selection
    bool bFound = false;
    var ParcelTypesEnum = await myParcelFabricLayer.GetParcelTypeNamesAsync();
    foreach (FeatureLayer mapFeatLyr in MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>())
    {
      foreach (string ParcelType in ParcelTypesEnum)
      {
        var layerEnum = await myParcelFabricLayer.GetParcelPolygonLayerByTypeNameAsync(ParcelType);
        foreach (FeatureLayer flyr in layerEnum)
        {
          if (flyr == mapFeatLyr)
          {
            bFound = mapFeatLyr.SelectionCount > 0;
            parcelPolygonLyr = mapFeatLyr;
            break;
          }
        }
        if (bFound) break;
      }
      if (bFound) break;
    }
    if (!bFound)
      return "Please select parcels to shrink to seeds.";
    var editOper = new EditOperation()
    {
      Name = "Shrink Parcels To Seeds",
      ProgressMessage = "Shrink Parcels To Seeds...",
      ShowModalMessageAfterFailure = true,
      SelectNewFeatures = true,
      SelectModifiedFeatures = false
    };
    var ids = new List<long>(parcelPolygonLyr.GetSelection().GetObjectIDs());
    var sourceParcelFeatures = new Dictionary<MapMember, List<long>>();
    sourceParcelFeatures.Add(parcelPolygonLyr, ids);
    editOper.ShrinkParcelsToSeeds(myParcelFabricLayer,SelectionSet.FromDictionary(sourceParcelFeatures));
    if (!editOper.Execute())
      return editOper.ErrorMessage;
  }
  catch (Exception ex)
  {
    return ex.Message;
  }
  return "";
});
if (!string.IsNullOrEmpty(errorMessage))
  MessageBox.Show(errorMessage, "Shrink Parcels To Seeds.");