code: func (u *Upgrade) CanUpgradeKubelets() bool {
  	// If there are multiple different versions now, an upgrade is possible (even if only for a subset of the nodes)
  	if len(u.Before.KubeletVersions) > 1 {
  		return true
  	}
  	// Don't report something available for upgrade if we don't know the current state
  	if len(u.Before.KubeletVersions) == 0 {
  		return false
  	}
  
  	// if the same version number existed both before and after, we don't have to upgrade it
  	_, sameVersionFound := u.Before.KubeletVersions[u.After.KubeVersion]
  	return !sameVersionFound
  }
docs: // CanUpgradeKubelets returns whether an upgrade of any kubelet in the cluster is possible