CouchbaseCluster.spec.monitoring.prometheus.image is missing default value

In the docs for the couchbase exporter (https://docs.couchbase.com/cmos/current/tutorial-kubernetes.html#deploy-couchbase) it says
If the couchbaseclusters.spec.monitoring.prometheus.image field is left unspecified, then the dynamic admission controller will automatically populate it with the most recent container image that was available when the installed version of the Autonomous Operator was released.
When trying to create a cluster without specifying a image value, I get an invalid yaml error:
error: error validating "cb-config.yaml": error validating data: ValidationError(CouchbaseCluster.spec.monitoring.prometheus): missing required field "image" in com.couchbase.v2.CouchbaseCluster.spec.monitoring.prometheus; if you choose to ignore these errors, turn validation off with --validate=false
It works when you add the image field.
 
The default value needs to be added