title: Dynamic Spring Kafka Listener
body: <p>I am using spring kafka with SPEL and trying to listen to different topics based on the value present in one of the property file.</p>
  
  <p>@KafkaListener(topics="#{kafkaTopics.getTopics().get('${key.in.property}')}")</p>
  
  <p>Now here getTopics is returning a Map of .</p>
  
  <p>All is working fine when I have some String[] being returned from get().</p>
  
  <p>But, in case if get() is returning "" ,i.e. I do not want to subscribe to any topic, then there is some issue.</p>
  
  <p>I am getting IllegalTopicException. <strong>Invalid Topic ''</strong>.</p>
  
  <p>Is there any way to solve this, if I do not want to listen to any topic at runtime?</p>