/**
  * @param array $mapping
  *
  * @return Metadata
  */
 private function getMetadata($mapping)
 {
     $metadata = new Metadata();
     $metadata->setAlias($mapping['alias']);
     $metadata->setPhpcrType($mapping['phpcr_type']);
     $metadata->setClass($mapping['class']);
     return $metadata;
 }
 /**
  * @return Metadata
  */
 private function getUnknownMetadata()
 {
     $metadata = new Metadata();
     $metadata->setAlias(null);
     $metadata->setPhpcrType(null);
     $metadata->setClass(UnknownDocument::class);
     return $metadata;
 }