code: func (proxier *Proxier) addServiceOnPort(service proxy.ServicePortName, protocol v1.Protocol, proxyPort int, timeout time.Duration) (*ServiceInfo, error) {
  	proxier.mu.Lock()
  	defer proxier.mu.Unlock()
  	return proxier.addServiceOnPortInternal(service, protocol, proxyPort, timeout)
  }
docs: // addServiceOnPort lockes the proxy before calling addServiceOnPortInternal.
  // Used from testcases.