(mongodb >=1.11.0)
MongoDB\Driver\Monitoring\CommandStartedEvent::getServiceId — Returns the load balancer service ID for the command
   When the driver is connected to a MongoDB cluster through a load balancer,
   the service ID corresponds to the serviceId field in the
   hello command response.
  
У цієї функції немає параметрів.
   Returns the load balancer service ID, or null if the driver is not
   connected to a load balancer.
  
