title: how to use @MetaDataKeyParam in the @Source method in Anypoint-Devkit
body: <p>I am developing a custom connector for generating Mule events.</p>
  
  <p>So I am using the <code>@Source</code> annotation above the method.</p>
  
  <p>I need to retrieve some metadata, and I also need to use the metadata keys as input during runtime. I have the following method signature with the mentioned annotations:</p>
  
  <pre class="lang-java prettyprint-override"><code>@Source(sourceStrategy = SourceStrategy.POLLING, pollingPeriod = 5000)
  public void getMessage(SourceCallback callback, @MetaDataKeyParam(affects = 
  MetaDataKeyParamAffectsType.OUTPUT) String eventType,, int count) 
  </code></pre>
  
  <p>Is there a way to implement dynamic metadata retrieval for <code>@Source</code> type i.e for callable module or event generator?</p>