code: public function serializeParameters($type, array $parameters)
      {
          $jobType = $this->registry->get($type);
          $indices = $jobType->getIndicesOfSerializableParameters();
          if (count($indices) < count($parameters)) {
              throw new \InvalidArgumentException(sprintf('More parameters provided for serialization than defined for job "%s"', $type));
          }
  
          $i = 0;
          $serializedParameters = array();
          foreach ($parameters as $parameter) {
              if (null == $parameter) {
                  $serializedParameters[] = null;
              } else {
                  $serializedParameters[] = $this->serializer->serialize($parameter, 'json', $this->getParamSerializationContext($jobType, $indices[$i]));
              }
              $i++;
          }
  
          $data = json_encode($serializedParameters);
          if (false === $data) {
              throw new \RuntimeException(sprintf('Serialization failed with error "%s"', json_last_error_msg()));
          }
  
          return $data;
      }
docs: Serializes the parameters of a job.
  
  @param string $type The job type
  @param array  $parameters
  @return string