/**
  * Returns the URI of the icon of the provided content.
  * 
  * @param  AbstractContent $content The content.
  * 
  * @return string|null              The icon URL if found, null otherwise.
  */
 public function getIcon(AbstractContent $content)
 {
     if (null === ($baseFolder = $this->getBaseFolder())) {
         return null;
     }
     $defaultImage = $content->getDefaultImageName();
     if ('/' === substr($defaultImage, 0, 1)) {
         $iconUrl = $defaultImage;
         $urlType = RouteCollection::IMAGE_URL;
     } else {
         $iconUrl = $this->resolveResourceThumbnail($defaultImage);
         $urlType = RouteCollection::RESOURCE_URL;
     }
     return $this->application->getRouting()->getUri($iconUrl, null, null, $urlType);
 }