title: @Reference annotation for class
body: <p>I have two case :</p>
  
  <ol>
  <li><p>@Reference anottation for field - I know how work this case, my servises bind so good </p></li>
  <li><p>But case @Reference anottation for class - I dont understand how it work 
  @Component(immediate = true)
  @Service(MyManager.class)
  @Reference(policy = ReferencePolicy.DYNAMIC, cardinality = ReferenceCardinality.OPTIONAL_MULTIPLE, referenceInterface = Messenger.class, bind = "bindMessenger", unbind = "unbindMessenger")
  public class MyManager {}</p></li>
  </ol>
  
  <p>What different between this situations ?</p>