trimWhitespace doesn't work for the service pub.flatFile:convertToValues

I get 1 csv file and convert it to bizdoc by using the service wm.tn.doc.ff:routeFlatFile.
after that, i create a new service and add the input parameter as bizdoc, and call the service pub.flatFile:convertToValues to convert previous csv file to FF and set flags/trimWhitespace to “both”, but the fields are not trim at all when i check the FF document, anyone can give me some advice?