Indeed, and remember this JSON message is going to a mainframe. Mainframes don't have much memory and typically process record-by-record, or event-by-event. So

Indeed, and remember this JSON message is going to a mainframe. Mainframes don't have much memory and typically process record-by-record, or event-by-event. So the implemenations probably streams the JSON in and constructs COPYBOOK from the payload before continuing to invoke the cobol. So the rework time might be to write a general purpose re-order layer that can re-order any imcoming message.