use null to overwrite value

.gitlab/development-values.yaml

 service:
   externalPort: 80
   internalPort: 80
-  commonName: ""
-  additionalHosts: {www.metager3.de}
+  additionalHosts:
+    - www.metager3.de
+  commonName: "null"
 ingress:
   annotations:
     certmanager.k8s.io/cluster-issuer: letsencrypt-prod