code: func (daemon *Daemon) GetNetworkDriverList() []string {
  	if !daemon.NetworkControllerEnabled() {
  		return nil
  	}
  
  	pluginList := daemon.netController.BuiltinDrivers()
  
  	managedPlugins := daemon.PluginStore.GetAllManagedPluginsByCap(driverapi.NetworkPluginEndpointType)
  
  	for _, plugin := range managedPlugins {
  		pluginList = append(pluginList, plugin.Name())
  	}
  
  	pluginMap := make(map[string]bool)
  	for _, plugin := range pluginList {
  		pluginMap[plugin] = true
  	}
  
  	networks := daemon.netController.Networks()
  
  	for _, network := range networks {
  		if !pluginMap[network.Type()] {
  			pluginList = append(pluginList, network.Type())
  			pluginMap[network.Type()] = true
  		}
  	}
  
  	sort.Strings(pluginList)
  
  	return pluginList
  }
docs: // GetNetworkDriverList returns the list of plugins drivers
  // registered for network.