title: Can't set Kafka retention policy to both compact and delete
body: <p>According to the below links I'm supposed to be able to set the <code>retention.policy</code> value to <code>"compact,delete"</code>.</p>
  
  <p><a href="https://issues.apache.org/jira/browse/KAFKA-4015" rel="nofollow noreferrer">https://issues.apache.org/jira/browse/KAFKA-4015</a></p>
  
  <p><a href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-71%3A+Enable+log+compaction+and+deletion+to+co-exist" rel="nofollow noreferrer">https://cwiki.apache.org/confluence/display/KAFKA/KIP-71%3A+Enable+log+compaction+and+deletion+to+co-exist</a></p>
  
  <p>However when I try to alter the retention policy by running:</p>
  
  <pre><code>./kafka-configs.sh --zookeeper $KAFKAZKHOSTS  --entity-type
   topics --alter --add-config cleanup.policy=compact,delete --entity-name topicname
  </code></pre>
  
  <p>I'm getting the following error:</p>
  
  <pre><code>requirement failed: Invalid entity config: all configs to be added must be in the format "key=val".
  </code></pre>