The "explain" command should not show "platform.gcp.privateDNSZone.id".

$ ./openshift-install version
./openshift-install 4.13.0-0.nightly-2023-01-07-232931
built from commit e284448f18f2d8c0d0c8f279b4b3c2806b77777c
release image registry.ci.openshift.org/ocp/release@sha256:f8be717d0aabf2e0a3bba1053c931294b9344acba56b5299854dc7044932075c
release architecture amd64

Always

1. try "openshift-install explain installconfig.platform.gcp" and make sure "privateDNSZone.id" is a valid field
2. providing a valid name or id for "platform.gcp.privateDNSZone.id" in install-config.yaml, along with some other valid IPI XPN settings, then "create cluster"  

ERROR failed to fetch Metadata: failed to load asset "Install Config": failed to create install config: invalid "install-config.yaml" file: platform.gcp.privateDNSZone.id: Forbidden: do not provide an ID for the private DNS zone. 

As "platform.gcp.privateDNSZone.id" is unsupported, the "explain" command should not show it.

FYI In https://issues.redhat.com/browse/CORS-2409, installer removed the support of GCP Private DNS Zone ID.

$ ./openshift-install version
./openshift-install 4.13.0-0.nightly-2023-01-07-232931
built from commit e284448f18f2d8c0d0c8f279b4b3c2806b77777c
release image registry.ci.openshift.org/ocp/release@sha256:f8be717d0aabf2e0a3bba1053c931294b9344acba56b5299854dc7044932075c
release architecture amd64
$ ./openshift-install explain installconfig.platform.gcp.privateDNSZone
KIND:     InstallConfig
VERSION:  v1RESOURCE: <object>
  PrivateDNSZone Technology Preview. PrivateDNSZone contains the zone ID and project where the Private DNS zone records will be created.FIELDS:
    id <string>
      ID Technology Preview. ID or name of the zone.
    project <string>
      ProjectID Technology Preview. When the ProjectID is provided, the zone will exist in this project. When the ProjectID is empty, the ProjectID defaults to the Service Project (GCP.ProjectID).

$ yq-3.3.0 r test2/install-config.yaml baseDomain
qe1.gcp.devcluster.openshift.com
$ yq-3.3.0 r test2/install-config.yaml metadata
creationTimestamp: null
name: jiwei-ocp04
$ yq-3.3.0 r test2/install-config.yaml credentialsMode
Passthrough
$ yq-3.3.0 r test2/install-config.yaml featureSet
TechPreviewNoUpgrade
$ yq-3.3.0 r test2/install-config.yaml platform
gcp:
  projectID: openshift-qe
  region: us-east1
  computeSubnet: installer-shared-vpc-subnet-2
  controlPlaneSubnet: installer-shared-vpc-subnet-1
  network: installer-shared-vpc
  networkProjectID: openshift-qe-shared-vpc
  publicDNSZone:
    id: qe1
  privateDNSZone:
    id: ipi-xpn-private-zone02
$ ./openshift-install create cluster --dir test2
ERROR failed to fetch Metadata: failed to load asset "Install Config": failed to create install config: invalid "install-config.yaml" file: platform.gcp.privateDNSZone.id: Forbidden: do not provide an ID for the private DNS zone.
$ 
$ gcloud dns managed-zones describe ipi-xpn-private-zone02
cloudLoggingConfig:
  kind: dns#managedZoneCloudLoggingConfig
creationTime: '2022-11-03T04:36:28.760Z'
description: Preserved private zone for IPI XPN
dnsName: jiwei-ocp04.qe1.gcp.devcluster.openshift.com.
id: '1281194096785275366'
kind: dns#managedZone
name: ipi-xpn-private-zone02
nameServers:
- ns-gcp-private.googledomains.com.
privateVisibilityConfig:
  kind: dns#managedZonePrivateVisibilityConfig
  networks:
  - kind: dns#managedZonePrivateVisibilityConfigNetwork
    networkUrl: https://www.googleapis.com/compute/v1/projects/openshift-qe-shared-vpc/global/networks/installer-shared-vpc
visibility: private
$ 
$ vim test2/install-config.yaml
$ yq-3.3.0 r test2/install-config.yaml platform
gcp:
  projectID: openshift-qe
  region: us-east1
  computeSubnet: installer-shared-vpc-subnet-2
  controlPlaneSubnet: installer-shared-vpc-subnet-1
  network: installer-shared-vpc
  networkProjectID: openshift-qe-shared-vpc
  publicDNSZone:
    id: qe1
  privateDNSZone:
    id: 1281194096785275366
$ ./openshift-install create cluster --dir test2
ERROR failed to fetch Metadata: failed to load asset "Install Config": failed to create install config: invalid "install-config.yaml" file: platform.gcp.privateDNSZone.id: Forbidden: do not provide an ID for the private DNS zone. 
$