protected function intervalGetLastTime()
 {
     $currentLastTime = parent::intervalGetLastTime();
     if (empty($currentLastTime)) {
         return null;
     }
     if (!in_array(Ess_M2ePro_Model_Synchronization_Task_Abstract::OTHER_LISTINGS, $this->getAllowedTasksTypes())) {
         return $currentLastTime;
     }
     $otherListingsLastTime = $this->getConfigValue('/amazon/other_listings/', 'last_time');
     if (empty($otherListingsLastTime)) {
         return null;
     }
     if (strtotime($otherListingsLastTime) < strtotime($currentLastTime)) {
         return $otherListingsLastTime;
     }
     return $currentLastTime;
 }