Is your feature request related to a problem?
I have a messaging application exclusively using streams for Cosmos document management. There are numerous instances where none or only partial (de)serialization is required, With the ChangeFeedProcessor you require a typed delegate which flows through the serializer, something I do not want because all I am doing with document is a block blob copy to cold storage.
I am using Orleans with a dedicated service grain responsible for the change feed, providing a convenient means to offload the work from the principal process flow that saved the document.

I will only do partial deserialization in order to determine how the stream will be routed. The current approach of the CFP requires both deserialization and serialization to move a message forward.

Describe the solution you'd like
A delegate providing the raw stream.

Describe alternatives you've considered
Adding an inline method to save to cold storage,