/**
  * {@inheritdoc}
  */
 public function findRootAssetMappings(Expression $expr)
 {
     $descriptors = $this->discoveryManager->findRootBindingDescriptors($this->exprBuilder->buildExpression($expr));
     $mappings = array();
     foreach ($descriptors as $descriptor) {
         $mappings[] = $this->bindingToMapping($descriptor->getBinding());
     }
     return $mappings;
 }