Hi @AlexO
Our forum is mainly focused on the general issue of Skype for Business Server troubleshooting. According to your description, your issue is related to development which is not in our support scope. The following idea is just for your reference.
In your provided document, it shows this API can still be used in Skype for Business on-prem Server. You could find the lists of supported SDKs and APIs for Skype for Business Server from this article.
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