title: Verfiy/Test Acknowledgment was called in spring boot kafka
body: <p>I've written integration tests for my Spring Boot Kafka (Consumer/Producer) service everything gone well. So I'm committing the offsets of my consumer manually after some processing.
  <strong>I want to verify whether <code>acknowledgment.acknowledge()</code> was called in the consumer. Is is to possible verify?</strong></p>
  <p>Here is my method signature of the service:</p>
  <pre><code>@KafkaListener(topics = {TOPIC_XXX_V1}, containerFactory = &quot;XXXListener&quot;)
      private void consumer(@Payload XXXXRequestEvent xxxxRequestEvent, Acknowledgment acknowledgment) {
  
  .....
  // do something with the database
  
  acknowledgment.acknowledge()
  </code></pre>
  <p>For the testing side I'm using <code>@SpyBean</code> for the Service and a <code>MockBean</code> for the database interaction. I want verify somehow whether in the test case the <code>.acknowledge()</code> was called. FYI: the <code>.acknowledge()</code> is a public abstract void method</p>