"num_retries": 2,
            "retry_host_predicate": [
             {
              "name": "envoy.retry_host_predicates.previous_hosts",
              "typed_config": {
               "@type": "type.googleapis.com/envoy.extensions.retry.host.previous_hosts.v3.PreviousHostsPredicate"
              }
             }
            ],
            "host_selection_retry_max_attempts": "5",

  optional string storageClassName = 3;

  // capacity is the value reported by the CSI driver in its GetCapacityResponse
  // for a GetCapacityRequest with topology and parameters that match the
  // previous fields.
  //
  // The semantic is currently (CSI spec 1.2) defined as:
  // The available capacity, in bytes, of the storage that can be used
  // to provision volumes. If not set, that information is currently

  local IMAGE="${2:-"${DEFAULT_KIND_IMAGE}"}"
  local CONFIG="${3:-}"
  local NOMETALBINSTALL="${4:-}"
  local CLEANUP="${5:-true}"

  check_default_cluster_yaml

  # Delete any previous KinD cluster
  echo "Deleting previous KinD cluster with name=${NAME}"
  if ! (kind delete cluster --name="${NAME}" -v9) > /dev/null; then
    echo "No existing kind cluster with name ${NAME}. Continue..."
  fi

  // Specifies how to treat concurrent executions of a Job.
  // Valid values are:
  //
  // - "Allow" (default): allows CronJobs to run concurrently;
  // - "Forbid": forbids concurrent runs, skipping next run if previous run hasn't finished yet;
  // - "Replace": cancels currently running job and replaces it with a new one
  // +optional
  optional string concurrencyPolicy = 3;

					return err
				}
				reader = in
				defer func() {
					if errClose := in.Close(); errClose != nil {
						log.Errorf("Error: close file from %s, %s", inFilename, errClose)

						// don't overwrite the previous error
						if err == nil {
							err = errClose
						}
					}
				}()
			}

			var writer io.Writer
			if outFilename == "" {
				writer = c.OutOrStdout()
			} else {

  optional string storageClassName = 3;

  // capacity is the value reported by the CSI driver in its GetCapacityResponse
  // for a GetCapacityRequest with topology and parameters that match the
  // previous fields.
  //
  // The semantic is currently (CSI spec 1.2) defined as:
  // The available capacity, in bytes, of the storage that can be used
  // to provision volumes. If not set, that information is currently

	conf := Config{}

	if err := json.Unmarshal(stdin, &conf); err != nil {
		return nil, fmt.Errorf("failed to parse network configuration: %v", err)
	}

	log.Debugf("istio-cni: Config is: %+v", conf)
	// Parse previous result. Remove this if your plugin is not chained.
	if conf.RawPrevResult != nil {
		resultBytes, err := json.Marshal(conf.RawPrevResult)
		if err != nil {
			return nil, fmt.Errorf("could not serialize prevResult: %v", err)

			tag, profile, humanReadableJoin(enabledComponents))
		if !Confirm(prompt, stdOut) {
			p.Println("Cancelled.")
			os.Exit(1)
		}
	}

	iop.Name = savedIOPName(iop)

	// Detect whether previous installation exists prior to performing the installation.
	if err := InstallManifests(iop, iArgs.Force, rootArgs.DryRun, kubeClient, client, iArgs.ReadinessTimeout, l); err != nil {

Note that clients can actually send three types of messages - requests, ACKs of previous pushes, and NACKs of previous pushes. Unfortunately, these are not clearly distinguished in the API, so there is some logic to split these out (`shouldRespond`).

#### Pushes

  optional string storageClassName = 3;

  // capacity is the value reported by the CSI driver in its GetCapacityResponse
  // for a GetCapacityRequest with topology and parameters that match the
  // previous fields.
  //
  // The semantic is currently (CSI spec 1.2) defined as:
  // The available capacity, in bytes, of the storage that can be used
  // to provision volumes. If not set, that information is currently