kakfaStream 与kafka partitions动态增

Partitions can be added to a Kafka topic dynamically. This example shows that an existing stream

 will not see the data published to the new partitions, and only when the existing streaming context is terminated

 and a new stream is started from a new context will that data be delivered.

kafka的主题分区可以动态增加，如果已经在运行的stream是不能发现新增的partition的数据的，必须重新启动一个新的stream。