Problem Definition

Migrating Team Calendar using ICS Export/Import to another Confluence instance causes data loss in the Who field in events.

Team Calendar can export Calendar into ICS.
Using this ICS Export/Import is currently the only supported method to migrate Team Calendar from one Confluence to another.

However, the Who field in the calendar events are being mapped by the user_key value which is often unique to each Confluence instance.
As an example, here's how a Calendar Birthday Event look like in the ICS Export:

BEGIN:VEVENT
DTSTAMP:20230410T040628Z
DTSTART;VALUE=DATE:20230405
DTEND;VALUE=DATE:20230406
SUMMARY:banana: bdayz
CATEGORIES:birthdays
SUBCALENDAR-ID:9c2f8b87-c50f-4b4b-bfbb-c08a2abb9fa3
PARENT-CALENDAR-ID:277bb4c3-43bb-4b7c-930f-57326913984a
PARENT-CALENDAR-NAME:
SUBSCRIPTION-ID:
SUBCALENDAR-TZ-ID:Australia/Sydney
SUBCALENDAR-NAME:My First Cal
EVENT-ID:1
EVENT-ALLDAY:true
UID:20230410T040616Z--10681091@localhost
DESCRIPTION:bdayz
ORGANIZER;X-CONFLUENCE-USER-KEY=402880418701dd54018701dddbc30000;CN=admin
 ;CUTYPE=INDIVIDUAL:mailto:admin@localhost.com
CREATED:20230410T040616Z
LAST-MODIFIED:20230410T040616Z
ATTENDEE;X-CONFLUENCE-USER-KEY=402880418740d4210187695760140000;CN=banana
 ;CUTYPE=INDIVIDUAL:mailto:banana@banana.banana
SEQUENCE:1
X-CONFLUENCE-SUBCALENDAR-TYPE:birthdays
TRANSP:TRANSPARENT
STATUS:CONFIRMED
END:VEVENT

In the example above, we see 2 users with their details below:

Difficulty on Migrating to Another Confluence

In the situation if both the admin and banana users exist in 2 different Confluence instances (eg: Source Confluence and Destination Confluence) — despite having the same username and email address, the user_key generated in user_mapping table between 2 Confluence instances will likely be different.

This means if the admin tries to migrate Team Calendar from Source Confluence to Destination Confluence, the Who field in the events will be lost upon import (since the user_key doesn't match).

Suggested Solution

Gives admin an option to have better mapping during ICS Import, such as using username or Email Address