After a restart of Jenkins, API usernames that had an uppercase character are converted to lowercase. The security profile can't find permissions for this new user and blocks the connection. Before the restart, it worked OK.

I'm using the built-in Jenkins database for storing users.

Expected behavior:

• Either convert the username on user-creation time immediately to a lower-case version for API usage and make sure it never changes (or)
• Do not convert when restarting

How to reproduce:

• Create a user with a capital in the name
• Verify that the user's API username has a capital
• (optional: create a security entry for this user using the username with the capital)
• Restart Jenkins
• Verify that the user's API username is now lowercase
• (optional: verify that logging in via API doesn't work work anymore)
• (optional: verify rhat after adding the lowercase-version of the API username to the security screen, everything works OK again)

Addendum:
Interestingly, the username used by the external tool doesn't have to be changed to the lower-case version (OpenStack's Jenkins Job Builder in my case). I'm not sure if this is because of behavior of the tool, or the behavior of the logging-in part in Jenkins.