Optional<Long> accountId = getAccountId();
if (accountId.isPresent()) {
UserFileUploadTracker tracker = ServiceLocator.instance().getInstance(
UserFileUploadTracker.class);
boolean registeredForUpload = tracker.tryToRegisterUserForFileUpload(accountId.get());
if (!registeredForUpload) {
log.error("User with id {} is already uploading something.", accountId.get());
respondWithError(response, "already uploading");
} else {
try {