A body containing raw binary data
Usage: Stream bodies are used to send arbitrary binary data such as
audio, video or any other file attachment.
The content-type can be overridden to something more specific like image/jpeg
or audio/wav for instance.
It is common to embed a stream body in a MultiPartBody to send additional information
with the binary file.
When possible, send a Content-Length header along with an octet-stream body. It may allow the receiver
end to better handle the loading.
A stream body is sent with the content-type application/octet-stream.