private Callback<Void> securityPostProcessRequestCallback() {
      return buildCallback(metrics.putSecurityPostProcessRequestMetrics, securityCheckResult -> {
        throw new RestServiceException(returnMessage, returnCode);
      }, uri, LOGGER, finalCallback);
    }
After {@link SecurityService#postProcessRequest} finishes, return response for the request.
@return a {@link Callback} to be used with {@link SecurityService#postProcessRequest}.
ambry-frontend/src/main/java/com/github/ambry/frontend/s3/S3BaseHandler.java