How can I add a sharee with WebDav ?

Hi

I finally succeeded in connecting to my NetCloud instance with Webdav to get files properties (as explaines on Basic APIs — Nextcloud latest Developer Manual latest documentation). I’d like to amend the sharees list (ie: share a file with someone). I tried to do a PROPPATCH with <d:propertyupdate and something like :

  <d:set>
  <nc:sharees>
     <nc:sharee>
        <nc:id>xxx-xxxx-xxx-xxx
        </nc:id>
     </nc:sharee>
  </nc:sharees>
  </d:set>

but I get an error “Argument #2 must be of type array, null given”

How shall I proceed to share or unshare a file through WebDav ?

Thx