title: Spring cloud stream kafka consumer that bind to multiple topics
body: <p><br>
  I want to configure one consumer application (will run on one JVM) that will bind to multiple topics.<br>
  Each "consume" (let say I have 2 topics to listen) method in the consumer application will be set with @StreamListener annotation and will be linked to specific topic.<br>
  Also i will configure each consumer in a different consumer-group.</p>
  
  <pre><code>spring.cloud.stream.bindings.&lt;consumer&gt;.group=&lt;group name&gt;
  </code></pre>
  
  <p>The idea is to consume messages from few topics, lets assume all with the same priority, manipulate them and pass them to the relevant microServices.<br></p>
  
  <p>How the consumer application will behave in such configuration?<br>
  The message will came one by one?<br>
  I need to implement each listner in a different thread?<br>
  Is this approach is good at all?</p>
  
  <p>Kafka version 0.8.2.1 (spotify image)<br>
  Spring-cloud-stram Brixton.RELEASE<br>
  Thanks.</p>