And if you want to go IE task approach, use attached IE task
1. In IE task FileUpload.xml, replace "GOLF_CART" container name with product name where this file needs to be uploaded. Or you can parametrize it.
2. Place IE task FileUpload.xml in <Windchill>\tasks\ext\company\object\
3. Restart Windchill
4. Call this IE Task (tested on Windchill 9.1) from Java (supplying Document Name as parameter) and stream required content file. You will need to handle authentication.
http://host.domain/Windchill/servlet/IE/tasks/ext/company/object/FileUpload.xml?file=<Document Name>