docs: protected void performRegistration(
          String discoveryService,
          RegistrationConfiguration registration,
          ServiceInstance instance,
          Publisher<HttpStatus> registrationObservable) {
  
          registrationObservable.subscribe(new Subscriber<HttpStatus>() {
              @Override
              public void onSubscribe(Subscription s) {
                  s.request(1);
              }
  
              @Override
              public void onNext(HttpStatus httpStatus) {
                  if (LOG.isInfoEnabled()) {
                      LOG.info("Registered service [{}] with {}", instance.getId(), discoveryService);
                  }
              }
  
              @Override
              public void onError(Throwable t) {
                  if (LOG.isErrorEnabled()) {
                      String message = getErrorMessage(discoveryService, t);
                      LOG.error(message, t);
                  }
                  if (registration.isFailFast() && instance instanceof EmbeddedServerInstance) {
                      ((EmbeddedServerInstance) instance).getEmbeddedServer().stop();
                  }
              }
  
              @Override
              public void onComplete() {
              }
          });
      }