code: public void write(JsonGenerator jsonGenerator) throws IOException {
      jsonGenerator.writeStartObject();
      jsonGenerator.writeStringField("poolGroupName", poolGroupName);
      jsonGenerator.writeStringField("poolName", poolName);
      jsonGenerator.writeEndObject();
    }
docs: Used to write the state of the PoolInfo instance to disk, when we are
  persisting the state of the ClusterManager
  
  @param jsonGenerator The JsonGenerator instance being used to write JSON
  to disk
  @throws IOException