/**
* Returns a read-only, detached document instance of the document at the
* specified path with the specified version name.
*
* The id of the returned document representing this version is not the id
* of the original document.
*
* @param null|string $className
* @param string $id id of the document
* @param string $versionName the version name as given by getLinearPredecessors
*
* @return the detached document or null if the document is not found
*
* @throws InvalidArgumentException if there is a document with $id but no
* version with $name
* @throws UnsupportedRepositoryOperationException if the implementation
* does not support versioning
*/
public function findVersionByName($className, $id, $versionName)
{
$this->errorIfClosed();
return $this->unitOfWork->findVersionByName($className, $id, $versionName);
}
