Adding an attribute to the CSR

I would like to add an additional attribute to the CSR (not the certificate) (e.g. a challenge password). It looks like the current API doesn't support custom attributes on the CSR itself, only for CertificateExtensions.

Is there a workaround on how to add the attribute manually?
Is this going to be supported for CSR anytime soon?

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#### Document Details

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* ID: 3e2b4f3b-b6ea-5e79-f986-4ca8abc55bc4
* Version Independent ID: 4b2145b8-b381-4e95-0f6c-23bdab8d00c0
* Content: [CertificateRequest Class (System.Security.Cryptography.X509Certificates)](https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.x509certificates.certificaterequest?view=netframework-4.7.2)
* Content Source: [xml/System.Security.Cryptography.X509Certificates/CertificateRequest.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Security.Cryptography.X509Certificates/CertificateRequest.xml)
* Product: **dotnet-api**
* GitHub Login: @mairaw
* Microsoft Alias: **mairaw**