Multipart endpoints assemble their own FormData and append each attachment to it, so they need the content as one
value rather than as a whole encoded body — that is what this provides, and createMultipartRequestBody is the
streaming alternative for callers building a request by hand.
Streaming content is collected here: a FormData part has to know its length, so a stream cannot stay lazy once it
goes into one.
One AttachmentInput as a single
FormData-appendable part.Multipart endpoints assemble their own
FormDataand append each attachment to it, so they need the content as one value rather than as a whole encoded body — that is what this provides, and createMultipartRequestBody is the streaming alternative for callers building a request by hand.Streaming content is collected here: a
FormDatapart has to know its length, so a stream cannot stay lazy once it goes into one.