curl -w "Elapsed: %{time_total}s\n" \
 -F file="@200mb.pdf" \
 http://localhost:8080/file-part \
 -o /dev/null -s
# Elapsed: 4.177509s
curl -w "Elapsed: %{time_total}s\n" \
 -F file="@200mb.pdf" \
 http://localhost:8080/part-event \
 -o /dev/null -s
# Elapsed: 4.224732s

curl -w "Elapsed: %{time_total}s\n" \
 -F file="@200mb.pdf" \
 http://localhost:8080/file-part \
 -o /dev/null -s
# Elapsed: 0.437359s
curl -w "Elapsed: %{time_total}s\n" \
 -F file="@200mb.pdf" \
 http://localhost:8080/part-event \
 -o /dev/null -s
# Elapsed: 0.317705s
#Test 19.53GB file
curl -w "\nElapsed: %{time_total}s\n" \
 -F file="@game.rar" \
 http://localhost:8080/file-part \
 -o /dev/null -s
# Elapsed: 27.586772s
curl -w "Elapsed: %{time_total}s\n" \
 -F file="@game.rar" \
 http://localhost:8080/part-event \
 -o /dev/null -s
# Elapsed: 18.328275s
#Test Multiple files
curl -w "Elapsed: %{time_total}s\n" \
 -F file="@200mb.pdf" \
 -F file="@game.rar" \
 http://localhost:8080/file-part \
 -o /dev/null -s
# Elapsed: 23.678042s
curl -w "Elapsed: %{time_total}s\n" \
 -F file="@200mb.pdf" \
 -F file="@game.rar" \
 http://localhost:8080/part-event \
 -o /dev/null -s
# Elapsed: 17.001363s

@PostMapping(path = "/file-part", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public Mono<Void> uploadFilePart(@RequestPart("file") FilePart file) {
 log.info("Received file part request {}", file.filename());
 return Mono.empty();
}
@PostMapping(path = "/part-event", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public Mono<Void> uploadPartEvent(@RequestBody Flux<PartEvent> allPartsEvents) {
 return allPartsEvents.windowUntil(PartEvent::isLast)
 .concatMap(p -> p.switchOnFirst((signal, partEvents) -> {
 if (signal.hasValue()) {
 PartEvent event = signal.get();
 if (event instanceof FormPartEvent formEvent) {
 return Mono.error(new RuntimeException("Unexpected event: " + event));
 } else if (event instanceof FilePartEvent fileEvent) {
 log.info("Received part event request {}", fileEvent.filename());
 return partEvents
 .ofType(FilePartEvent.class)
 .doOnNext(file -> DataBufferUtils.release(file.content()))
 .then(Mono.empty());
 } else {
 return Mono.error(new RuntimeException("Unexpected event: " + event));
 }
 } else {
 return partEvents;
 }
 })).then();
}