@Override
  public void validateRequest(RestRequest restRequest, Callback<Void> callback) {
    Exception exception = null;
    serverMetrics.securityServiceValidateRequestRate.mark();
    if (!isOpen) {
      exception = new RestServiceException("ServerSecurityService is closed", RestServiceErrorCode.ServiceUnavailable);
    } else if (restRequest == null) {
      throw new IllegalArgumentException("restRequest is null");
    }
    callback.onCompletion(null, exception);
  }
Default implementation of {@link ServerSecurityService} for Ambry that doesn't do any validations.
ambry-server/src/main/java/com/github/ambry/server/AmbryServerSecurityService.java