public function appendNode(DOMElement $artifact_node, $artifact_id)
 {
     $list_of_changesets = $artifact_node->getElementsByTagName('changeset');
     if ($list_of_changesets->length == 0) {
         return;
     }
     $permissions = $this->dao->searchPermsForArtifact($artifact_id);
     if (!count($permissions)) {
         return;
     }
     $last_changeset_node = $list_of_changesets->item($list_of_changesets->length - 1);
     $field_node = $this->node_helper->createElement('field_change');
     $field_node->setAttribute('field_name', 'permissions_on_artifact');
     $field_node->setAttribute('type', 'permissions_on_artifact');
     $field_node->setAttribute('use_perm', '1');
     foreach ($permissions as $row) {
         $ugroup_node = $this->node_helper->createElement('ugroup');
         $ugroup_node->setAttribute('ugroup_id', $row['ugroup_id']);
         $field_node->appendChild($ugroup_node);
     }
     $last_changeset_node->appendChild($field_node);
 }