title: Issue Symfony 3.4 “object not found by the @ParamConverter annotation”
body: <p>I have an issue with "object not found by the @ParamConverter annotation" on Symfony 3.4 when I try to delete selected items of table. I think it's an issue when I try to get the "spectacle" with the id ("findOneBy()")</p>
  
  <p>This is my code (html.twig) :</p>
  
  <pre><code>&lt;form method="delete" action="{{ path('admin_spectacle_delete_selected') }}"&gt;
  &lt;button class="content-red btn btn-fabop" type="submit"&gt;&lt;i class="fa fa-trash"&gt;&lt;/i&gt; Tout supprimer&lt;/button&gt;
  
  &lt;div class="table-responsive"&gt;
      &lt;table id="myTable" class="table table-bordered table-hover table-striped"&gt;
          &lt;thead&gt;
              &lt;tr&gt;
                  &lt;th style="text-align:center;"&gt;&lt;input type="checkbox" id="all"&gt;&lt;/th&gt;
                  &lt;th&gt;Nom&lt;/th&gt;
                  &lt;th&gt;Lieu&lt;/th&gt;
                  &lt;th&gt;Date spectacle&lt;/th&gt;
                  &lt;th&gt;Annee&lt;/th&gt;
                  &lt;th&gt;Actions&lt;/th&gt;
              &lt;/tr&gt;
          &lt;/thead&gt;
          &lt;tbody&gt;
          {% for spectacle in spectacles %}
              &lt;tr&gt;
                  &lt;td id="spectacle{{ spectacle.id }}"&gt;&lt;input type="checkbox" name='multiSelected[]' value="{{ spectacle.id }}"&gt;&lt;/td&gt;
                  &lt;td&gt;{{ spectacle.nom }}&lt;/td&gt;
                  &lt;td&gt;{{ spectacle.lieu }}&lt;/td&gt;
                  &lt;td&gt;{{ spectacle.dateSpectacle }}&lt;/td&gt;
                  &lt;td&gt;{{ spectacle.annee }}&lt;/td&gt;
                  &lt;td&gt;
                      &lt;a class="content-blue btn-fabop btn" href="{{ path('admin_spectacle_show', { 'id': spectacle.id }) }}"&gt;&lt;i class="fa fa-search"&gt;&lt;/i&gt; Détail&lt;/a&gt;
                      &lt;a class="content-purple btn-fabop btn" href="{{ path('admin_spectacle_edit', { 'id': spectacle.id }) }}"&gt;&lt;i class="fa fa-pencil"&gt;&lt;/i&gt; Edition&lt;/a&gt;
                      &lt;a class="content-red btn-fabop btn" href="{{ path('admin_spectacle_delete_confirmed', { 'id': spectacle.id }) }}"&gt;&lt;i class="fa fa-trash"&gt;&lt;/i&gt; Suppression&lt;/a&gt;
  
  
                  &lt;/td&gt;
              &lt;/tr&gt;
          {% endfor %}
          &lt;/tbody&gt;
      &lt;/table&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p></p>
  
  <p>and controller :</p>
  
  <pre><code>  /**
  * Confirmation delete
  *
  * @Route("/deleteSelected", name="admin_spectacle_delete_selected")
  */
  public function deleteSelectedAction(Request $request)
  {
  
      $items_selected_id = $request-&gt;get('multiSelected');
  
        $em = $this-&gt;getDoctrine()-&gt;getManager();
        $repository = $em-&gt;getRepository(Spectacle::class);
        foreach($items_selected_id as $item_id) {
  
          $spectacle = $repository-&gt;findOneById($item_id);
  
          if (!$spectacle) {
              throw $this-&gt;createNotFoundException(
                  'No spectacle found for id '.$spectacle
              );
          }
          else{
              $em-&gt;remove($spectacle);
          }
        }
        $em-&gt;flush();  
        return $this-&gt;redirectToRoute('admin_spectacle_index');
  }
  </code></pre>
  
  <p>Thank you for your response !!</p>