Return Employee ExternalId with Timesheet Advanced Search

@operator

I'm running an advanced search for timesheets but in order to map back to our other systems I need to return the external id of the employee.

The current C# function is like this

     public List<TimeSheet> FindTimesheetsByLastModified(DateTime lastModified) {          TimeSheetSearchAdvanced tsa = new TimeSheetSearchAdvanced() {          criteria = new TimeSheetSearch() {            timeEntryJoin = new TimeEntrySearchBasic() {              lastModified = new SearchDateField() {                @operator = SearchDateFieldOperator.after,                operatorSpecified = true,                searchValue = lastModified,                searchValueSpecified = true              }            }          }        };          SearchResult result = _service.search(tsa);          if (!result.status.isSuccess) {          throw new ApplicationException("Timesheet search failed", EnumerateErrorsToException(result.status.statusDetail));        }          List<TimeSheet> records = result.recordList.Select(t => (TimeSheet)t).ToList();          return records;        }