title: behaviour and busy indicator
body: <p>I have such things in my Java code:</p>
  
  <pre><code>//...omitted some not revelant code
  AjaxIndicatorAppender indicator = new AjaxIndicatorAppender();
  final RequiredTextField&lt;String&gt; nickField = new RequiredTextField&lt;String&gt;( "nick", new PropertyModel&lt;String&gt;( this, "nickValue" ) );
  formContainer.add( nickField );
  indicator.bind(nickField);
  nickField.add( new MyValidatingBehaviour( (Form) formContainer, "onkeyup", Duration.ONE_SECOND, indicator ) );
  
  //...
  
  private class MyValidatingBehaviour extends AjaxFormValidatingBehavior implements IAjaxIndicatorAware
  {
      AjaxIndicatorAppender indicator;
  
      private MyValidatingBehaviour( Form&lt;?&gt; form, String event, final Duration throttleDelay, AjaxIndicatorAppender indicator )
      {
          super( form, event );
          this.setThrottleDelay( throttleDelay );
          this.indicator = indicator;
      }
  
      @Override
      public String getAjaxIndicatorMarkupId()
      {
          return indicator.getMarkupId();
      }
  }
  </code></pre>
  
  <p>But nothing happens, there's no any indicator, am I doing something wrong? Couldnt find any example for my case</p>