Add support to add custom AllowedApplicationsPolicy

[PeterKvayt]

I have the following situation.
I created a custom application (section on UI) and I want to add an authorization policy as umbraco does.
Umbraco has the following classes:

• AllowedApplicationHandler
• AllowedApplicationRequirement
• BackOfficeAuthPolicyBuilderExtensions

These classes above are protected and I can't use them in my own code to add custom AllowedApplicationsPolicy. Currently I need tp copy-paste them.

Can someone give me advice, maybe there is already a solution or we need to make these classes public?