Reporting an Issue or Missing Feature

On a newly created tenant I was applying several policies through Microsoft365DSC and noticed that due to a bug there, which I still didn't report or created a PR for, it applied a Tenant CDN policy with ExcludeRestrictedSiteClassifications set to what I had previously applied on IncludeFileExtensions which of course is wrong, but to my surprise I couldn't set ExcludeRestrictedSiteClassifications back to empty with Set-PnPTenantCdnPolicy as it was the default in the tenant since PolicyValue is a string and can't be null. The same applies for IncludeFileExtensions, these 2 parameters by default are null in the tenant and the cmdlet should be able to restore this but can't. FYI, I was able to resolve this by running the following M365 CLI command on a PS prompt:

m365 spo cdn policy set --cdnType Public --policy ExcludeRestrictedSiteClassifications --value @()

Also note that even though that command solved my issue it also has a problem since applying it with $null instead of @() the value it stores in the tenant is TRUE which is incorrect, but that is a separate issue that should be checked with M365 CLI's team.

Expected behavior

Set-PnPTenantCdnPolicy should accept for both IncludeFileExtensions and ExcludeRestrictedSiteClassifications a null policy value, both parameters should have AllowEmptyString in https://github.com/pnp/powershell/blob/dev/src/Commands/Admin/SetTenantCdnPolicy.cs

Actual behavior

Set-PnPTenantCdnPolicy fails if policy value parameter is null since it's a string and mandatory

Steps to reproduce behavior

Set-PnPTenantCdnPolicy -CdnType "Public" `
    -PolicyType 'IncludeFileExtensions' `
    -PolicyValue $null

or

Set-PnPTenantCdnPolicy -CdnType "Public" `
    -PolicyType 'ExcludeRestrictedSiteClassifications' `
    -PolicyValue $null

What is the version of the Cmdlet module you are running?

1.12.0, the reason for the old version is due to a compatibility issue with M365DSC and therefore cannot be upgraded, but the problem is present on latest version of https://github.com/pnp/powershell/blob/dev/src/Commands/Admin/SetTenantCdnPolicy.cs

Which operating system/environment are you running PnP PowerShell on?

• Windows
• Linux
• MacOS
• Azure Cloud Shell
• Azure Functions
• Other : please specify