Create secret manager secrets with lables that don't have keys

[zyang71]

In this Secret Manager documentation, it says label values can be empty, and I was able to create labels without values on the UI console.

How do I do this with gcloud or Terraform? When I create resource "google_secret_manager_secret" with Terraform passing label like below it doesn't create label at all.

resource "google_secret_manager_secret" "secret-with-empty-value-label" {
  secret_id="test-secret"
  labels={key=""}
  replication {auto {}}
}