在使用的时候会用到bootstrap，与broker.list

本以为是两个参数，其实是实现一个功能，查看源代码后发现broker.list是旧版本命令

1. val bootsrapServers = {
2. if(properties.containsKey("metadata.broker.list"))
3. warn("Kafka producer configuration contains 'metadata.broker.list'. This configuration is deprecated . Samza has been upgraded " +
4. "to use Kafka's new producer API. Please update your configurations based on the documentation at http://kafka.apache.org/documentation.html#newproducerconfigs")
5. Option(properties.get("bootstrap.servers"))
6. .getOrElse(throw new SamzaException("No bootstrap servers defined in config for %s." format systemName))
7. .asInstanceOf[String]

现在直接可以使用新版本命令bootstrap。