Automatic scheduling of calendar collections was introduced by CalDav extension which was a protocol built upon WebDav. (There is CardDav protocol introduced parallel to CalDav for transferring of vcard information) CalDav was introduced by the IETF from RFC 6638 but Lightning’s implementation was done before the final version was introduced. Referring to the draft version 4.
I went through both versions to identify changes between them and a list was prepared. I explored the bugzilla and the calendar blog to find bugs related to CalDav properties and found some of them that can be used to track the implementation.
I started with the bug used to implement the CalDav in Lightning. https://bugzilla.mozilla.org/attachment.cgi?id=334246&action=diff
Also, hope I will be working the code around this bug to implement proposed schedule-default-calendar-URL Dav property in Lightning. https://bugzilla.mozilla.org/show_bug.cgi?id=351745
My next step is to setup the Sogo server for testing features. It seems to be a very much updated and well aligned with the RFC 6638.
Also, I will be using next few days to hack into the code base to get a better understanding about the implementation along with RFCs. New bugs for each feature in the proposal are planned to be posted in the Bugzilla to get feedback and guidance from the community.