Issue Summary

After upgrading Jira 9.x, the assignee of the Jira events cannot be displayed on the Team Calendars if the Jira Description field contains a newline (shift+enter while the Description field is on 'Visual' mode, not new paragraph by using just enter).

This is reproducible on Data Center: yes

Steps to Reproduce

1. Instal Confluence and Jira (tested with Confluence 7.19.3/TC 7.3.21 and all Jira 9.x versions - 9.0.0, 9.1.1, 9.2.0, 9.3.1)
2. Create Application Links between them.
3. Create an issue and add the below text for the 'Description' field in the text mode

   test
   test
   

4. Save the issue and note its key.
5. Assign the ticket to yourself.
6. Navigate to Confluence and create a Calendar there.
7. Click the button near the newly created calendar's name
8. Click 'Add Event'
   1. Select the relevant Jira server (it may automatically be chosen)
   2. Give a name to this event
   3. Choose JQL and enter the below JQL query:

      key = <key-of-the-jira-issue>
      

      Replace the <key-of-the-jira-issue> with the noted Jira issue key.

   4. Choose 'Issue Created Date' from the 'Single Date' column that is displayed after entering the JQL query.
9. Save the event.

Expected Results

The event will be displayed in the Team Calendars and when it is clicked, the 'Assignee' field should be displayed too.

Actual Results

The 'Assignee' field is displayed as 'Unassigned' even though it is assigned to the user. There are no logs or any faulty indications in the Confluence logs.

If the DEBUG log is enabled for the com.atlassian.confluence.extra.calendar3 class you can see the event data that is coming from Jira:

2022-11-15 17:41:48,232 DEBUG [http-nio-48090-exec-2 url: /rest/calendar-services/1.0/calendar/events.json; user: admin] [confluence.extra.calendar3.DefaultCalendarManager] toSubCalendarEvent VEVENT to transform is: BEGIN:VEVENT
X_JIRA_ISSUE_DATE_FIELD_EDITABLE:false
X-JIRA-ISSUE-DATE-FIELD;X-JIRA-ISSUE-DATE-FIELD-KEY=created:Created
UID;X-JIRA-UID-STATIC=true:22c3280a-bb1c-42dd-8e24-65660ed13af3-TP1-2-created@localhost
SUMMARY:Assignee issue-1
DTSTART;TZID=Europe/Brussels:20221115T130844
DTEND;TZID=Europe/Brussels:20221115T130844
DESCRIPTION:test
\NTEST:X-JIRA-ASSIGNEE\;X-JIRA-ASSIGNEE-ID=admin:Jira Admin
DTSTAMP:20221115T120844Z
CREATED:20221115T120844Z
LAST-MODIFIED:20221115T164142Z
X-JIRA-ISSUE-KEY:TP1-2
X-JIRA-STATUS:Backlog
X-JIRA-RESOLUTION:
END:VEVENT

You can see that the 'DESCRIPTION' field and 'X-JIRA-ASSIGNEE' field merged in the same line.

Workaround

Removing the newline character solves the issue but it is not a feasible workaround for most cases.