The usage of "compute.platform.gcp.serviceAccount" needs to be clarified, and also the installation failure.

4.14.0-0.nightly-2023-07-16-230237

Always

1. "openshift-install explain installconfig.compute.platform.gcp.serviceAccount"
2. "create cluster" with an existing install-config having the field configured 

1. It tells "The provided service account will be attached to control-plane nodes...", although the field is under compute.platform.gcp.
2. The installation failed on creating install config, with error "service accounts only valid for master nodes, provided for worker nodes".

1. shall "explain" command tell the field "serviceAccount" under "installconfig.compute.platform.gcp"?
2. please clarify how "compute.platform.gcp.serviceAccount" should be used

FYI the corresponding PR: https://github.com/openshift/installer/pull/7308

$ openshift-install version
openshift-install 4.14.0-0.nightly-2023-07-16-230237
built from commit c2d7db9d4eedf7b79fcf975f3cbd8042542982ca
release image registry.ci.openshift.org/ocp/release@sha256:e31716b6f12a81066c78362c2f36b9f18ad51c9768bdc894d596cf5b0f689681
release architecture amd64
$ openshift-install explain installconfig.compute.platform.gcp.serviceAccount
KIND:     InstallConfig
VERSION:  v1RESOURCE: <string>
  ServiceAccount is the email of a gcp service account to be used for shared vpn installations. The provided service account will be attached to control-plane nodes in order to provide the permissions required by the cloud provider in the host project.

$ openshift-install explain installconfig.controlPlane.platform.gcp.serviceAccount
KIND:     InstallConfig
VERSION:  v1RESOURCE: <string>
  ServiceAccount is the email of a gcp service account to be used for shared vpn installations. The provided service account will be attached to control-plane nodes in order to provide the permissions required by the cloud provider in the host project.

$ yq-3.3.0 r test2/install-config.yaml platform
gcp:
  projectID: openshift-qe
  region: us-central1
  computeSubnet: installer-shared-vpc-subnet-2
  controlPlaneSubnet: installer-shared-vpc-subnet-1
  network: installer-shared-vpc
  networkProjectID: openshift-qe-shared-vpc
$ yq-3.3.0 r test2/install-config.yaml credentialsMode
Passthrough
$ 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-0718b
$ yq-3.3.0 r test2/install-config.yaml compute
- architecture: amd64
  hyperthreading: Enabled
  name: worker
  platform:
    gcp:
      ServiceAccount: ipi-xpn-minpt-permissions@openshift-qe.iam.gserviceaccount.com
      tags:
      - preserved-ipi-xpn-compute
  replicas: 2
$ yq-3.3.0 r test2/install-config.yaml controlPlane
architecture: amd64
hyperthreading: Enabled
name: master
platform:
  gcp:
    ServiceAccount: ipi-xpn-minpt-permissions@openshift-qe.iam.gserviceaccount.com
    tags:
    - preserved-ipi-xpn-control-plane
replicas: 3
$ 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: compute[0].platform.gcp.serviceAccount: Invalid value: "ipi-xpn-minpt-permissions@openshift-qe.iam.gserviceaccount.com": service accounts only valid for master nodes, provided for worker nodes 
$