title: blur event is not working in select2js
body: <p>I used <code>select2</code> js(version 4) for my current project, and i need to perform operation on <code>blur</code> event of <code>select2 element</code>. My code is as below.</p>
  
  <pre><code>&lt;div class="form-group"&gt;
     &lt;label for=""&gt;Select all report Number(s)&lt;/label&gt;
     &lt;select class="js-example-basic-multiple js-states form-control" id="id_label_multiple" name="list" multiple="multiple"&gt;
        &lt;option value=""&gt;&lt;/option&gt;
           @foreach($reports as $item)
              &lt;option value="{{$item-&gt;report_no}}"&gt;{{$item-&gt;report_no}}&lt;/option&gt;
           @endforeach
     &lt;/select&gt;
   &lt;/div&gt;
  </code></pre>
  
  <p>javascript code</p>
  
  <pre><code>$(".js-example-basic-single").select2({
       placeholder: 'Select Seller'                       
  });
  $("#id_label_multiple").on('blur', function () {
       alert('Call Blur Evenet');
  });
  </code></pre>
  
  <p>other events are working perfect such as <code>change</code>. but something went wrong with blur event. </p>