private JsonNode particleListToJson(List<Particle> particleList) {
    JsonNode jsonNode;

    if (particleList == null) {
      jsonNode = JsonNodeFactory.instance.objectNode();
      logger.info("Null particleList, returning empty json");
    } else {
      jsonNode = Json.toJson(particleList);
    }
    return jsonNode;
  }
Converts a list of particles to json
@param particleList Particle List
@return JsonNode
app/com/linkedin/drelephant/tuning/ParamGenerator.java