Duplicate email check failed when username has some upper case characters

Issue Summary

When using JCMA to migrate individual projects to the cloud, users may see this
error:

Multiple users have the same email address
This is caused by the duplicate email check failed when the username has some upper case characters and some project data contains both user-refs and export treats them as two different user keys

Steps to Reproduce

1. access JCMA GUI <Server_URL>/secure/migration-app-action.jspa#/plan-configuration
2. select "chose what to migrate"
3. select "Projects, users and groups"
4. select desired projects
5. select "Only users and groups related to the selected projects"
6. select "Preserve Group Membership"
7. users should see the ERROR "Multiple users have the same email address"

Expected Results

Users should be able to complete the migration of individual projects via JCMA

Actual Results

Users may see this error:

Multiple users have the same email address

Workaround

User should migrate all the users/groups separately, then, via XML import, manually migrate the projects