namespace is defined as:

```yaml
defaultNamespace: istio-system
```

and namespaces are specialized for the gateway feature and its components:

```yaml
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
  namespace: istio-operator
spec:
  components:
    ingressGateways:
    - name: istio-ingressgateway
      enabled: true
      namespace: istio-gateways
```

	if un.GetAPIVersion() == istioV1Alpha1.IstioOperatorGVK.GroupVersion().String() {
		if un.GetKind() == istioV1Alpha1.IstioOperatorGVK.Kind {
			if err := checkFields(un); err != nil {
				return nil, err
			}
			// IstioOperator isn't part of pkg/config/schema/collections,
			// usual conversion not available.  Convert unstructured to string
			// and ask operator code to check.

		},
	})
}

// TestManifestGenerateHelmValues tests whether enabling components through the values passthrough interface works as
// expected i.e. without requiring enablement also in IstioOperator API.
func TestManifestGenerateHelmValues(t *testing.T) {
	runTestGroup(t, testGroup{
		{
			desc:       "helm_values_enablement",
			diffSelect: "Deployment:*:istio-egressgateway, Service:*:istio-egressgateway",

| -istio.test.kube.helm.values | string | Manual overrides for Helm values file. Only valid when deploying Istio. |
| -istio.test.kube.helm.iopFile | string | IstioOperator spec file. This can be an absolute path or relative to the repository root. Defaults to "tests/integration/iop-integration-test-defaults.yaml". |