title: how do i test Exactly Once Semantics working in my kafka streams application
body: <p>i have a Kafka Streams DSL application, we have a requirement on exactly once processing, for the same i have added the configuration</p>
  <pre><code>streamConfig.put(processing.gurantee, &quot;exactly_once&quot;);
  </code></pre>
  <p>I am using kafka 2.7
  I have 2 queries</p>
  <ol>
  <li>what's the difference between exactly_once and exactly_once_beta</li>
  <li>how do i test this functionality to be sure my messages are getting processed only once</li>
  </ol>
  <p>Thanks!</p>