} else {
		versionCount[configVersion] = 1
	}
}

const distributionTrackingDisabledErrorString = "pilot version tracking is disabled " +
	"(To enable this feature, please set PILOT_ENABLE_CONFIG_DISTRIBUTION_TRACKING=true)"

func poll(ctx cli.Context,
	cmd *cobra.Command,
	acceptedVersions []string,
	targetResource string,
	proxyID string,
	opts clioptions.ControlPlaneOptions,

		"PILOT_DRAINING_LABEL",
		"istio.io/draining",
		"If not empty, endpoints with the label value present will be sent with status DRAINING.",
	).Get()

	EnableDistributionTracking = env.Register(
		"PILOT_ENABLE_CONFIG_DISTRIBUTION_TRACKING",
		false,
		"If enabled, Pilot will assign meaningful nonces to each Envoy configuration message, and allow "+
			"users to interrogate which envoy has which config from the debug interface.",
	).Get()

	}
	writeJSON(w, resources, req)
}

const DistributionTrackingDisabledMessage = "Pilot Version tracking is disabled. It may be enabled by setting the " +
	"PILOT_ENABLE_CONFIG_DISTRIBUTION_TRACKING environment variable to true."

func (s *DiscoveryServer) distributedVersions(w http.ResponseWriter, req *http.Request) {
	if !features.EnableDistributionTracking {
		w.WriteHeader(http.StatusConflict)