Using non-destructive site import maps user content based on username and not email.

Issue Summary

User content is mapped based on Username and not email address

Steps to Reproduce

1. Create a user called admin2 on your server instance (lets say this user has email xyz_user@atlassian.com)
2. Create some content with this user in the Server instance.
3. Generate a backup on the server instance
4. Have a user in Cloud with the username admin2 but with another email (lets say abc_user@atlassian.com)
5. Perform a Jira site import on the site from the backup from Step 3.
6. Choose the option to merge users.

Expected Results

User Content for user xyz_user@atlassian.com is mapped from Server to Cloud based on email address.

Actual Results

User Content for user xyz_user@atlassian.com is mapped from Server to Cloud based on username matching. So the content gets mapped to user with email abc_user@atlassian.com

Workaround

Content will be mapped correctly if the usernames match in the Jira Server and Cloud instances.