Problem Definition

Currently, the External System Import does import new users, but nowhere in the documentation (Importing issues) or during the import process does it specify that it will create these users.

The documentation does mention what it will do with newly imported users, but not that it does it in the first place.

The warning also does not occur in the process itself.
The problem here is that it can bring an instance over its licensing limit, and in JIRA Cloud, the new invoice is automatically generated and the billing admin may not see this has happened until they have already been charged.

Suggested Solution

Update the documentation to specifically mention it will import and create new users, and put along the import process that it will do so and this may cause their bill to go up.