public new Feature CreateRow( 
   RowBuffer featureBuffer
)

public async Task CreatingAFeature()
{
  string message = String.Empty;
  bool creationResult = false;

  await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
  {
    using (Geodatabase geodatabase = new Geodatabase(new DatabaseConnectionFile(new Uri("path\\to\\sde\\file\\sdefile.sde"))))
    using (FeatureClass enterpriseFeatureClass = geodatabase.OpenDataset<FeatureClass>("LocalGovernment.GDB.FacilitySite"))
    {
      //var geodatabase = new Geodatabase(new FileGeodatabaseConnectionPath(uri)) for a File GDB
      //
      //var shapeFileConnPath = new FileSystemConnectionPath(uri, FileSystemDatastoreType.Shapefile);
      //var shapefile = new FileSystemDatastore(shapeFileConnPath);
      //var table = shapefile.OpenDataset<Table>(strShapeFileName); for a Shape file

      //declare the callback here. We are not executing it ~yet~
      EditOperation editOperation = new EditOperation();
      editOperation.Callback(context =>
      {
        FeatureClassDefinition facilitySiteDefinition = enterpriseFeatureClass.GetDefinition();
        int facilityIdIndex = facilitySiteDefinition.FindField("FACILITYID");

        using (RowBuffer rowBuffer = enterpriseFeatureClass.CreateRowBuffer())
        {
          // Either the field index or the field name can be used in the indexer.
          rowBuffer[facilityIdIndex] = "wMain";
          rowBuffer["NAME"] = "Griffith Park";
          rowBuffer["OWNTYPE"] = "Municipal";
          rowBuffer["FCODE"] = "Park";
          // Add it to Public Attractions Subtype.
          rowBuffer[facilitySiteDefinition.GetSubtypeField()] = 820;

          List<Coordinate2D> newCoordinates = new List<Coordinate2D>
          {
              new Coordinate2D(1021570, 1880583),
              new Coordinate2D(1028730, 1880994),
              new Coordinate2D(1029718, 1875644),
              new Coordinate2D(1021405, 1875397)
            };

          rowBuffer[facilitySiteDefinition.GetShapeField()] = new PolygonBuilderEx(newCoordinates).ToGeometry();

          using (Feature feature = enterpriseFeatureClass.CreateRow(rowBuffer))
          {
            //To Indicate that the attribute table has to be updated
            context.Invalidate(feature);
          }
        }

      }, enterpriseFeatureClass);

      try
      {
        creationResult = editOperation.Execute();
        if (!creationResult) message = editOperation.ErrorMessage;
      }
      catch (GeodatabaseException exObj)
      {
        message = exObj.Message;
      }
    }
  });

  if (!string.IsNullOrEmpty(message))
    MessageBox.Show(message);
}