title: Kafka Consumer get assigned partitions for a specific topic
body: <p>I'm working with a Kafka Consumer, and only subscribe to one topic.  I want to return only the assigned partitions from the topic for each consumer.  I am running  four instances of the consumer in the same group, and reading a topic with 8 partitions.</p>
  
  <p>I know I can use the assignment() method, but it looks like that returns the topic name and partition in the format of - (i.e. topic1-0, topic1-1, etc).  Is there a better way of getting the partition only without having to parse the value returned from the assignment() method?</p>