Allow to call Register-PnPEntraIDApp with a certificate without private key

[jackpoz]

Type

• Bug Fix
• New Feature
• Sample

Related Issues?

Fixes #5129

What is in this Pull Request ?

Allow to call Register-PnPEntraIDApp with a certificate without private key, so .cer instead of .pfx .
The private key is not needed when uploading a certificate to an app registration in Entra ID.

Here's the behavior with the PR:

The app registration works fine, see below a test case (notice how the pfx is used in this case with Connect-PnPOnline) :

[Copilot]

Pull Request Overview

This PR removes the private key validation check when using an existing certificate with the Register-PnPAzureADApp cmdlet. The removed code ensured that certificates provided via the -CertificatePath parameter contain a private key before proceeding with app registration.

• Removes the HasPrivateKey validation check for certificates loaded from a file path
• Eliminates the associated error message that would inform users when their certificate lacks a private key

[Copilot]

The error message states 'Failed to import private key certificate' but uses PSArgumentNullException, which is semantically incorrect as this is not about a null argument but rather an incorrect password. Consider using PSArgumentException instead to better reflect the actual error condition. Note: This issue exists in the current code and is not introduced by this PR, but since the surrounding code is being modified, it would be appropriate to fix this as well.

Suggested change

	throw new PSArgumentNullException(nameof(CertificatePassword), $"Failed to import private key certificate. Ensure the correct password is provided for parameter: {nameof(CertificatePassword)}");
	throw new PSArgumentException($"Failed to import private key certificate. Ensure the correct password is provided for parameter: {nameof(CertificatePassword)}", nameof(CertificatePassword));