[kronolith] External Attendees get dropped using Thunderbird Lightning

[Abhi Jadhav]

Create an event through Thunderbird Lightning.
Add an external attendee and send out invite
Check the event in Thunderbird, the event looks intact with external 
attendees listed
Synchronize calendars
Check the event in Horde UI - the external attendees have dropped off.
Check the event in Thunderbird - the external attendees have dropped off.

Is this a bug? or is this something I can fix on my end?

Abhi