private synchronized void save(Map<String, Object> refData) {
        String key = buildCacheKey(refData);
        try {
            refData.forEach((field, value) -> jedis.hset(key, field, String.valueOf(value)));
        } finally {
            if (keyExpiredTime != 0) {
                jedis.expire(key, keyExpiredTime);
            }
        }
    }
1. build key from map.
 2. save key and value.
 3. set expired time for key when keyExpiredTime has been set.
@param refData
redis5/redis5-sink/src/main/java/com/dtstack/flink/sql/sink/redis/RedisOutputFormat.java