CCMA fails to migrate space with team calendars due to duplicate event type key

Issue Summary

During migration of spaces with CCMA 3.9.4, if team calendars are migration along with spaces (no dark feature flag used), then Space migration fails.

This is reproducible on Data Center: (no)

Steps to Reproduce

1. Create a new migration plan in CCMA 3.9.4
2. Select Space(s) to be migrated
3. Run Migration

Expected Results

Spaces and related team calendars are migrated successfully

Actual Results

The below exception is thrown in the atlassian-confluence.log file:

2024-01-20 17:07:10,218 ERROR [com.atlassian.migration-StepExecutionService:thread-29] [agent.service.stepexecutor.ProgressTracker] error Step failed, message: Import to cloud failed. Message: ERROR: duplicate key value violates unique constraint "AO_950DC3_TC_SUBCALS_pkey"; To investigate this error please provide the trace id xxxxxxxxxxxxx to Atlassian support.To investigate this error please provide the trace id xxxxxxxxxxxx to Atlassian support.

Workaround

If the error shows up with one of these constraints:

• "AO_950DC3_TC_SUBCALS_pkey"
• "AO_950DC3_TC_REMINDER_SETTINGS_pkey"
• "AO_950DC3_TC_CUSTOM_EV_TYPES_pkey"

That means there is remnant Team Calendar space data from a previous migration and there are two options for workarounds (below). 

Option 1:

1. Ensure the space is completely deleted. 
2. Atlassian support can help with deleting a space fully using internal scripts. 

Option 2:

1. Create a plan without the failed spaces
2. Apply the dark feature flag migration-assistant.disable.team-calendars-migration to skip team calendars migration.
   This will not migrate team calendars across.
3. Create a plan to migrate the problematic spaces
4. Migrate team calendars separately either manually or contact Atlassian Support.
   • See How to Migrate Team Calendars data from Server to Cloud

Option 3:

1. If the error shows up with any other constraints besides those listed above, retry the migration.