code: public function getServiceConfig()
  	{
  		return array(
  			'factories' => array(
  				'CronHelper\Service\CronService' => function ($serviceManager) {
  					$mainConfig = $serviceManager->get('config');
  					$serviceConfig = array();
  
  					if (is_array($mainConfig)) {
  						if (array_key_exists('cron_helper', $mainConfig)) {
  							$serviceConfig = $mainConfig['cron_helper'];
  						}
  					}
  
  					$cronService = new CronService($serviceConfig);
  					return $cronService;
  				},
  			),
  		);
  	}
docs: Retrieve configuration for the service manager
  
  @return array