/**
  * Registers a custom repository class for the document class.
  *
  * @param string $repositoryClassName The class name of the custom repository.
  */
 public function setCustomRepositoryClassName($repositoryClassName)
 {
     $this->customRepositoryClassName = $this->fullyQualifiedClassName($repositoryClassName);
     if ($this->customRepositoryClassName && !class_exists($this->customRepositoryClassName)) {
         throw MappingException::repositoryNotExisting($this->name, $this->customRepositoryClassName);
     }
 }