The autoUpload feature wasn't targeted for 3.3 (
ICE-6637), but at some point it was backported when backporting the support for Servlet 3 multi-part uploads ( ICE-9273, r40315). This commit also included some code for the multiple file upload mode, even though it wasn't targeted for 3.3 either. The 'multiple' attribute also exists in 3.3 but it causes an error when trying to use it.
ICE-6204 and all subsequent fixes and improvements to the multiple file upload mode.