/**
  * returns the changes happened since the provided syncToken which is the content sequence
  *
  * @param string $syncToken
  * @return array
  */
 public function getChanges($syncToken)
 {
     $result = parent::getChanges($syncToken);
     $newResult = array();
     $backend = Calendar_Controller_Event::getInstance()->getBackend();
     foreach ($result as $action => $value) {
         if (!is_array($value)) {
             $newResult[$action] = $value;
             continue;
         }
         $uids = $backend->getUidOfBaseEvents(array_keys($value));
         $newResult[$action] = array();
         foreach ($uids as $row) {
             $newResult[$action][$row[0]] = $row[0] . $this->_suffix;
         }
     }
     return $newResult;
 }