Issue Summary

Description: The Customfield optimizer doesn't check for mandatory fields in a project. If the CFO is run while a new project is being set up and no issues are created yet, it can mistakenly recommend removing the field from the project.

Steps to replicate

1. Create a new project with a custom field that's marked mandatory.
2. Run the Custom Field Optimizer
3. Observe that it shows the custom field as unused

Workaround

There is no workaround applicable. The above leads to having to re-create custom fields which is what we would want to prevent.