pod.
Some volume types allow the Kubelet to change the ownership of that volume
to be owned by the pod:

1. The owning GID will be the FSGroup
2. The setgid bit is set (new files created in the volume will be owned by FSGroup)
3. The permission bits are OR'd with rw-rw----

If unset, the Kubelet will not modify the ownership and permissions of any volume.
Note that this field cannot be set when spec.os.name is windows.²