/**
  * @return mixed
  */
 public function accept(Tracker_Artifact_ChangesetValueVisitor $visitor)
 {
     return $visitor->visitPermissionsOnArtifact($this);
 }
 /**
  * @return mixed
  */
 public function accept(Tracker_Artifact_ChangesetValueVisitor $visitor)
 {
     return $visitor->visitOpenList($this);
 }