/**
  * Set the HTML code for the button.
  *
  * @param GetPasteRootButtonEvent $event The event being emitted.
  *
  * @param string                  $value The value returned by the callback.
  *
  * @return void
  */
 public function update($event, $value)
 {
     if ($value === null) {
         return;
     }
     $event->setHtml($value);
     $event->stopPropagation();
 }