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
                    }
                }
            }
        }
    });
}