Example 15.1 Step 7 - Selflink missing in some outputs

Hi

I am not seeing the line selfLink in some of my outputs. The example shows following line 16 and 17:
16 selfLink: /api/v1/namespaces/kube-system/secrets/certificate-
17 controller-token-wnrwh

My output looks like:
kubectl -n kube-system get secrets certificate-controller-token-7nndj -oyaml
apiVersion: v1
data:
ca.crt: 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
namespace: a3ViZS1zeXN0ZW0=
token: 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
kind: Secret
metadata:
annotations:
kubernetes.io/service-account.name: certificate-controller
kubernetes.io/service-account.uid: db041296-3adb-4b37-8784-1dc7cf4b3df5
creationTimestamp: "2021-06-18T17:01:20Z"
name: certificate-controller-token-7nndj
namespace: kube-system
resourceVersion: "294"
uid: c4c81897-fbd0-4a17-864e-a8c9989d82e8
type: kubernetes.io/service-account-token

Since I had seen it a few times, I was curious about that particular line - what it is and when it shows up.