How to submit a large binary using multipart-form file stream

[oldefezziwig]

I am trying to do a CreateAsync() passing a large Binary (like 20 mb) and the FHIR server I'm working with is returning back a RequestEntityTooLarge response code with the following error message:

further diagnostics: The requested binary is too large to handle. Please submit a multipart-form file stream instead

Is there a way to override how FhirClient is doing the SendAsync to in this case do it as a multipart-form file stream? We are passing a HttpClientEventHandler into the constructor for FhirClient. Can it be done there? Or elsewhere perhaps?