I think V2MarkupServiceImpl.doGetResource() simply needs to process formParameters.getUploadContexts()
In order to test:
1. Deploy the reference primefaces3-portlet demo (version 3.1.0-BETA2 or higher)
2. Create a WSRP Producer for the PrimeFaces3 Portlet
3. Create a WSRP Consumer for the producer URL with portlet named "WSRP PrimeFaces3"
4. Add the "WSRP PrimeFaces3" portlet to a new portal page
5. Upload a file with the PrimeFaces Ajax-based file upload feature by choosing a file and clicking "Upload"