// Register three groups
	handler.AddGroup(metav1.APIGroup{Name: "x"})
	handler.AddGroup(metav1.APIGroup{Name: "y"})
	handler.AddGroup(metav1.APIGroup{Name: "z"})
	// Register three additional groups that come earlier alphabetically
	handler.AddGroup(metav1.APIGroup{Name: "a"})
	handler.AddGroup(metav1.APIGroup{Name: "b"})
	handler.AddGroup(metav1.APIGroup{Name: "c"})

)

// GroupManager is an interface that allows dynamic mutation of the existing webservice to handle
// API groups being added or removed.
type GroupManager interface {
	AddGroup(apiGroup metav1.APIGroup)
	RemoveGroup(groupName string)
	ServeHTTP(resp http.ResponseWriter, req *http.Request)
	WebService() *restful.WebService
}

// rootAPIsHandler creates a webservice serving api group discovery.

    install|upgrade)

        # Create fess group if not existing
        if ! getent group "$FESS_GROUP" > /dev/null 2>&1 ; then
            echo -n "Creating $FESS_GROUP group..."
            addgroup --quiet --system "$FESS_GROUP"
            echo " OK"
        fi

        # Create fess user if not existing
        if ! id $FESS_USER > /dev/null 2>&1 ; then
            echo -n "Creating $FESS_USER user..."

if ! getent passwd istio-proxy >/dev/null; then
    if command -v useradd >/dev/null; then
        groupadd --system istio-proxy
        useradd --system --gid istio-proxy --home-dir /var/lib/istio istio-proxy
    else
        addgroup --system istio-proxy
        adduser --system --group --home /var/lib/istio istio-proxy
    fi
fi

if [ ! -e /etc/istio ]; then
   # Backward compat.
   ln -s /var/lib/istio /etc/istio
fi

			Name:             apiGroupInfo.PrioritizedVersions[0].Group,
			Versions:         apiVersionsForDiscovery,
			PreferredVersion: preferredVersionForDiscovery,
		}

		s.DiscoveryGroupManager.AddGroup(apiGroup)
		s.Handler.GoRestfulContainer.Add(discovery.NewAPIGroupHandler(s.Serializer, apiGroup).WebService())
	}
	return nil
}

// InstallAPIGroup exposes the given api group in the API.