According to the ChangeStreamDocument api, there are no getter methods for txnNumber and lsid.

From the manual, these fields do exist when the operation is part of a transaction.

Would you be able to extend the ChangeStreamDocument class to include the above fields?

Is this related to CSHARP-2406?

I did try to implement my own POJO to use in ChangeStreamIterable.withDocumentClass(). I got as far as registering the class's codec into the MongoClient.codecRegistry(). However, I was not successful. If there is a recommended approach without using the getters, please let me know.