WebDAV -- utilize REPORT DAV:principal-property-search
CalDAV and CardDAV show the calendars owned by the user by referencing them over the calendar-home-set and addressbook-home-set. WebDAV collections belonging to other users cannot be obtained using the home-sets, neither can shared collections, not beloning in practice to any user.
For finding more CalDAV/CardDAV collections, the specification of the latter offers the DAV:principal-property-search REPORT. E.g. on my system
curl -XREPORT -D- -H"Depth: 0" -u me:pw -H"Content-Type: application/xml" --data '<?xml version="1.0" encoding="UTF-8" ?>
<D:principal-property-search xmlns:D="DAV:">
<D:property-search>
<D:prop><D:displayname/></D:prop>
<D:match>sandra</D:match>
</D:property-search>
<D:prop><C:addressbook-home-set xmlns:C="urn:ietf:params:xml:ns:carddav"/><D:displayname/></D:prop>
</D:principal-property-search>' https://server/dav/principals/
returns
HTTP/2 207
Date: Mon, 27 Aug 2018 20:51:16 GMT
Content-Type: application/xml; charset=utf-8
Vary: Accept-Encoding, Brief, Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:carddav">
<D:response>
<D:href>/dav/principals/user/sandra/</D:href>
<D:propstat>
<D:prop>
<C:addressbook-home-set><D:href>/dav/addressbooks/user/sandra/</D:href></C:addressbook-home-set>
<D:displayname>sandra</D:displayname>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
and using <D:match>s</D:match>
returns even more data.
The application is that users can find this way shared collections without owner, of interest for all users, and also collections of other persons, that decided to share a collection (e.g. one of their calendars).
- Teach Evolution for already configured WebDAV-collection accounts to discover using DAV:principal-property-search more collections, and make the latter part of the collection account.