p-fileupload how to add a header in onBeforeUpload

[atulmith@gmail.com]

Hi,
Can anyone please point me to a doc telling as to how to write a REST service to consume the p-fileupload component for multiple file uploads.

How to add a header to "onBeforeUpload($event)" function to add this
headers.append('Content-Type', 'multipart/form-data');

Doing this will allow my rest service to be consumed by the fileupload component
Thanks,