Handling metadata.ManagedFields

[nrb]

kubernetes/kubernetes#72947 introduced ManagedFields into Kubernetes v1.18.

We need to determine whether or not Velero needs to do anything special with these at restore time, such as clear them off the object with the resetMetadataAndStatus function, or if they're already handled.

[nrb]

This appears to be part of server-side apply per https://kubernetes.io/blog/2020/04/01/kubernetes-1.18-feature-server-side-apply-beta-2/

Per https://kubernetes.io/docs/reference/using-api/server-side-apply/#field-management, Velero should not remove these fields and we should update resetMetadataAndStatus to reflect that. One caveat is that we may not be able to restore objects with these fields on pre-Kuberetes 1.18 clusters, but I think that may be minor as we don't technically support downgrades anyway.

Additionally, this metadata may be useful in making decisions about what to restore as opposed to using the last-applied-configuration annotation, which is subject to change.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

Closing the stale issue.

[ywk253100]

Fixed by #5853