ObservedGeneration is lost on two Ready state updates

[burmanm]

What happened?

If an update to Spec did not modify the StatefulSet (and as such causing the Updating status to be triggered) the ObservedGeneration is never updated.

The ObservedGeneration is only updated if State is changed, but Ready -> Ready even if generation has changed will not trigger this. And as such, we will remain in the wrong ObservedGeneration. This could cause unintentional restart on updates also.

What did you expect to happen?

ObservedGeneration is updated when we have finished the reconcile.

How can we reproduce it (as minimally and precisely as possible)?

Make a change that doesn't fix StatefulSet, such as abuse a bug in Canary upgrades.

cass-operator version

1.20

Kubernetes version

1.28

Method of installation

No response

Anything else we need to know?

No response