Which version of XWiki are you using ?
There is some issue that makes some code empty the file upload list.
Can you try by posting to a page with that in the URL ?xpage=plain
Also you should be able to do this without going to the internal API.
There is addAttachment in Document
Here is a
Hi, I want to create a page allowed to upload more files together
using FileUploadPlugin. I created 2 documents but the FileUploadPlugin
seems not work, the data return is null and the document
MySpace.Upload is attached with a file 0KB. Anyone can explain me why
this happens ? And how to fix ?