public IReadOnlyList<Field> GetFields()

public async Task JoiningWithWhereQueryDef()
{
  await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
  {
    using (Geodatabase geodatabase = new Geodatabase(new DatabaseConnectionFile(new Uri("path\\to\\sde\\file"))))
    {
      QueryDef municipalEmergencyFacilitiesQueryDef = new QueryDef
      {
        SubFields = "EmergencyFacility.OBJECTID, EmergencyFacility.Shape, EmergencyFacility.FACILITYID, FacilitySite.FACILITYID, FacilitySite.FCODE",
        Tables = "EmergencyFacility, FacilitySite",
        WhereClause = "EmergencyFacility.FACNAME = FacilitySite.NAME AND EmergencyFacility.JURISDICT = 'Municipal'",
      };

      using (RowCursor rowCursor = geodatabase.Evaluate(municipalEmergencyFacilitiesQueryDef, false))
      {
        while (rowCursor.MoveNext())
        {
          using (Row row = rowCursor.Current)
          {
            Feature feature = row as Feature;
            Geometry shape = feature.GetShape();

            long objectID = Convert.ToInt64(row["EmergencyFacility.OBJECTID"]);
            String featureCode = Convert.ToString(row["FacilitySite.FCODE"]);

            IReadOnlyList<Field> fields = feature.GetFields(); //Contains one ArcGIS.Core.Data.Field objects for every subfield
          }
        }
      }
    }
  });
}