The .metadata.generation field is updated if and only if the value at the .spec subpath changes.
Additionally, if the spec does not change, .metadata.generation is not updated.
This is a must-have for the controller-runtime work, if we don't have
this, the generation field will always be incremented, resulting in a
endless reconcile loop.
Signed-off-by: Sébastien Han <seb@redhat.com>