I have set a security scheme to allow third party developers to see only a sub-set of issues in the project. (by purpose they are in one project)
By having 2 security levels; one for all users (including the role "third party) and one for internal users only.
The security level is set by a custom field "classification" with 2 values (radio button) "internal only" and "internal and external".
I grant only the role "product manager" the permission to change security settings
Third parties do need Edit permissions to report progress and link issues.
With all these settings "third parties" still can change the security setting of the issue.
My question: How can I prevent the role "third party" to change the custom field that sets the security level and at the same time gives the role "third party" the permission to edit fields on the issues that are visible to them?