docs: protected void performDeregistration(String discoveryService, RegistrationConfiguration registration, Publisher<HttpStatus> deregisterPublisher, String applicationName) {
          if (registration.isFailFast()) {
  
              try {
                  Flowable.fromPublisher(deregisterPublisher).blockingFirst();
                  if (LOG.isInfoEnabled()) {
                      LOG.info("De-registered service [{}] with {}", applicationName, discoveryService);
                  }
              } catch (Throwable t) {
                  if (LOG.isErrorEnabled()) {
                      LOG.error("Error occurred de-registering service [" + applicationName + "] with " + discoveryService + ": " + t.getMessage(), t);
                  }
              }
          } else {
              deregisterPublisher.subscribe(new Subscriber<HttpStatus>() {
                  @Override
                  public void onSubscribe(Subscription subscription) {
                      subscription.request(1);
                  }
  
                  @Override
                  public void onNext(HttpStatus httpStatus) {
                      if (LOG.isInfoEnabled()) {
                          LOG.info("De-registered service [{}] with {}", applicationName, discoveryService);
                      }
                  }
  
                  @Override
                  public void onError(Throwable t) {
                      if (LOG.isErrorEnabled()) {
                          LOG.error("Error occurred de-registering service [" + applicationName + "] with " + discoveryService + ": " + t.getMessage(), t);
                      }
                  }
  
                  @Override
                  public void onComplete() {
  
                  }
              });
          }
      }