code: public String pipelineWriteHMSET(String key, DataGenerator dataGenerator, String hm_key_prefix) {
          Map<String, String> map = new HashMap<>();
          String hmKey = hm_key_prefix + key;
          map.put((hmKey + "__1"), (key + "__" + dataGenerator.getRandomValue() + "__" + key));
          map.put((hmKey + "__2"), (key + "__" + dataGenerator.getRandomValue() + "__" + key));
  
          DynoJedisPipeline pipeline = jedisClient.get().pipelined();
          pipeline.hmset(hmKey, map);
          pipeline.expire(hmKey, 3600);
          pipeline.sync();
  
          return "HMSET:" + hmKey;
      }
docs: writes with an pipelined HMSET
  
  @param key
  @return the keys of the hash that was stored.