Turns a payload into an options object that can be passed to a fetch call by setting the necessary headers and method. Note that this method creates a multipart/form-data stream under the hood. If possible, a JSON payload should be created instead for performance reasons.

Turns a payload into an options object that can be passed to a fetch call by setting the necessary headers and method. May only be called for payloads P that let requiresFormDataUpload(P) return false.

Determines for a given payload if it may be sent as JSON, or if it has to be uploaded via multipart/form-data. Returns true in the latter case and false in the former.