Research the principle of metadata.generation value increase
1 Background
Use kubebuilder to develop a vpa-related operator. This operator will watch all vpa creation, deletion and update in the cluster. controller-runtime provides predict to filter out unnecessary events, and use predicate.GenerationChangedPredicate to filter out vpa update status. However, it was found that the status update of vpa (recommended value updated by vpa-recommender) also triggered Reconcile.