title: select2 version 4 ajax data : results not appearing in control
body: <p>Since I have switched to version 4 of the select2 plugin, my ajax calls do not work anymore.</p>
  
  <p>I get a response in the form of an array which prints ok in the console but the results don't show in the select2 control.</p>
  
  <p>http response :</p>
  
  <pre><code>{"results":{"id":"ok","term":"ok","description":"ok"}}
  </code></pre>
  
  <p>My code :</p>
  
  <pre><code>            $(function(){
                  $('#appbundle_marketplace_product_ingredient_barcode').select2({
                      minimumInputLength: 3,
                      ajax:
                      {
                          delay: 250,
                          url: "{{ path('search_barcode') }}",
                          dataType: 'json',
                          debug: true,
                          data: function (params) {
  //                            console.log(params.term);
                              return {barcode: params.term};},
                          processResults: function (data) {
                              console.log(data);
                              return data;
                          }
                      }
                  });
              });
  </code></pre>
  
  <p>the data printed in the console is the following object :</p>
  
  <pre><code>Object {results: Object}
  results: Object
    description: "ok"
    id: "ok"
    term: "ok"
  __proto__: Object
  __proto__: Object
  </code></pre>
  
  <p>How can I have the select2 display a result in the dropdown, then click the result to have it selected ?</p>
  
  <p>Thanks a lot,</p>