createUrl
Get a Map attachment url pair with request/response RSocket API. Takes nothing as argument in payload.
Creates two urls, one for the end-user to upload its attachment and the other acts as a download link which can send to its recipient.
Returns a HubPayload encoded in ProtoBuf format. In case the operation was successful the HubPayload contains data with the resulted Map containing an HttpMethod as a key and values representing the appropriate URL. If an error has occurred during request with minio server it returns an error with code 503
.