// +optional
  optional string clusterIP = 3;

  // ClusterIPs is a list of IP addresses assigned to this service, and are
  // usually assigned randomly.  If an address is specified manually, is
  // in-range (as per system configuration), and is not in use, it will be
  // allocated to the service; otherwise creation of the service will fail.

- the IP allocator in v1.17.0 can return errors such as `the cluster IP <ip> for service <service-name> is not within the service CIDR <cidr>; please recreate` in the logs of the kube-apiserver. The cause is incorrect CIDR calculations if the service CIDR (`--service-cluster-ip-range`) is set to bits lower than `/16`. This is fixed in http://issue.k8s.io/86534 and will be resolved in v1.17.1.

    * Action required:
    * Anyone who generated server cert for admission webhooks need to regenerate the cert. Previously, when generating server cert for the admission webhook, the CN value doesn't matter. Now you must set it to the DNS name of the webhook service, i.e., `<service.Name>.<service.Namespace>.svc`.

- Added validation to ensure that if `service.kubernetes.io/topology-aware-hints` and `service.kubernetes.io/topology-mode` annotations are both set, they are set to the same value.Also Added deprecation warning if `service.kubernetes.io/topology-aware-hints` annotation is used. ([#116612](https://github.com/kubernetes/kubernetes/pull/116612), [@robscott](https://github.com/robscott))...

    * Two api fields are defined correspondingly:
        * Service.Spec.ExternalTrafficPolicy <- 'service.beta.kubernetes.io/external-traffic' annotation.
        * Service.Spec.HealthCheckNodePort <- 'service.beta.kubernetes.io/healthcheck-nodeport' annotation.

- Fixes service account token admission error in clusters that do not run the service account token controller ([#87029](https://github.com/kubernetes/kubernetes/pull/87029), [@liggitt](https://github.com/liggitt)) [SIG Auth]

  - `--service-account-issuer`, should be set to a URL identifying the API server that will be stable over the cluster lifetime.
  - `--service-account-key-file`, set to one or more files containing one or more public keys used to verify tokens.

* Cluster federation servers have changed the location in etcd where federated services are stored, so existing federated services must be deleted and recreated. Before upgrading, export all federated services from the federation server and delete the services. After upgrading the cluster, recreate the federated services from the exported data. ([#37770](https://github.com/kubernetes/kubernetes/pull/37770), [@enj](https://github.com/enj))

Action required:

    * Master: convert service CIDR to list  `--service-cluster-ip-range=<CIDR>,<CIDR>` and make sure `IPv6DualStack` feature flag is turned on. The flag is validated and used as the following:
    * 1. `--service-cluster-ip-range[0]` is consider primary service range, and will be used for any service with `Service.Spec.IPFamily = nil` or any service in the at the time of turning on the feature flag.