Radicale/radicale/tests/static/proppatch1.xml

<?xml version="1.0" encoding="utf-8"?>
<D:propertyupdate xmlns:D="DAV:">
  <D:set>
    <D:prop>
      <I:calendar-color xmlns:I="http://apple.com/ns/ical/">#BADA55</I:calendar-color>
    </D:prop>
  </D:set>
</D:propertyupdate>