public function getNextRoundId($roundId)
    {
       $this->_ensureRounds();

       if ($this->_rounds && $roundId) {
           $next = false;
           foreach ($this->_rounds as $currentRoundId => $round) {
               if ($next) {
                   return $currentRoundId;
               }
               if ($currentRoundId == $roundId) {
                   $next = true;
               }
           }

           return null;

       } elseif ($this->_rounds) {
           end($this->_rounds);
           return key($this->_rounds);
       }
    }