Implementing Data Export

@GetMapping(value = "/orders/export.csv", produces = "text/csv")
public ResponseEntity<StreamingResponseBody> export() {
    StreamingResponseBody body = out -> {
        try (var w = new OutputStreamWriter(out, UTF_8);
             var p = new PrintWriter(w)) {
            p.println("id,customer,total");
            orderRepo.streamAll().forEach(o ->
                p.printf("%s,%s,%d%n", o.id(), csv(o.customerName()), o.total().cents()));
        }
    };
    return ResponseEntity.ok()
        .header("Content-Disposition", "attachment; filename=orders.csv")
        .body(body);
}

StreamingResponseBody body = out -> {
    try (JsonGenerator g = mapper.createGenerator(out)) {
        g.writeStartArray();
        orderRepo.streamAll().forEach(o -> g.writeObject(toDto(o)));
        g.writeEndArray();
    }
};