private async Task <IEnumerable <RootIndexRow> > WriteValuesGroupToFile(IAsyncGrouping <string, KeyValuePair <string, string> > fileGroup,
string originFilename)
{
var values = await fileGroup.OrderBy(kvp => kvp.Key).Select(kvp => kvp.Key).ToListAsync();
var indexFileName = fileGroup.Key;
return(await _indexFileWriter.UpdateIndexFileWithValues(values, indexFileName, originFilename));
}
