GKE Terraform Kubernetes App validation Failure for Terraform

Getting error while publishing Terraform Kubernetes App. on GCP marketplace.

{
  "taskReports": [
    {
      "taskType": "EXECUTE_TERRAFORM_PLAN",
      "taskExecutionStatus": "ISSUES_FOUND",
      "digest": "Failed to execute terraform plan for some versions.",
      "errorMessage": "Error validating Terraform zip: Marketplace UI deployments must declare a variable 'goog_cm_deployment_name'. This variable specifies the name of the deployment, and should be used to avoid resource name collisions across deployments\n"
    }
  ]
}

Possible solutions I have tried:

I have changed variable.tf file to include variable:

variable "goog_cm_deployment_name" {
  description = "Name of the Google Cloud Marketplace deployment. Auto-populated by the Marketplace UI."
  type        = string
}

Added below in metadata.yaml file:

interfaces:
    variables:
      # ---- GCP / cluster ---------------------------------------------------
      - name: goog_cm_deployment_name
        description: The name of the deployment.
        varType: string
        required: true

Still, I am unable to resolve this error on GCP marketplace. Can anyone help?

Also, I am getting multiple errors one by one(like solving one and getting another), is there any documentation where all requirement listed and sample terraform kubernetes app also available?

Thanks