/**
  * Applies the model mapping strategy for a converted resource to determine the final target type.
  * The strategy is NOT applied if $source['__type'] is set (overriding was allowed then, otherwise an exception would have been thrown earlier).
  *
  * @param string $originalTargetType The original target type determined so far
  * @param PersistentResource $resource The resource that is to be converted to a media file.
  * @param array $source the original source properties for this type converter.
  * @return string Class name of the media model to use for the given resource
  */
 protected function applyModelMappingStrategy($originalTargetType, PersistentResource $resource, array $source = array())
 {
     $finalTargetType = $originalTargetType;
     if (!isset($source['__type'])) {
         $finalTargetType = $this->assetModelMappingStrategy->map($resource, $source);
     }
     return $finalTargetType;
 }