Transform a list of operation arguments to an http request message body. This method searches for parameters with swagger / openAPI specification `in: body` or `in: formData`. `body` parameters are expected to be R vectors or lists, and are transformed to JSON using `jsonlite::toJSON()`. `formData` parameters are treated as is, so must be specified (e.g., using `httr::upload_file()`) by the caller. Interpretation of `formData` parameters require that the `op_def` includes `consumes: multipart/form-data`.
get_message_body(op_def, x)A list representation of the swagger / openAPI description of the operation.
A list representation of the operation arguments provided by the user.
A JSON character representation (for `body`) or list of objects (for `formData`) representing the parameters `x`.