code: function instantiateDrivers(config, defaultDriverInstance) {
      config.actionConfigs.forEach(action => {
              action.driverInstance=action.driver?action.driver():defaultDriverInstance;
      });
      return config;
  }
docs: Instantiate the driver for each configuration. If no driver has been specified,
  this will provide the config with a default driver.
  
  The default driver is usually a null driver - which has no impact.