[Nut-upsdev] Should NUT have a way to optionally report last-update timestamps (or equivalent deemed safe)?

[Edgar Fuß]

> All that said, I could see a "data_updated: [unix-epoch]" which is
> basically the last time we heard data from the device.  But I would want
> to see if adding a validity binary sensor is good enough.
For the NUT-to-collectd interface (sysutils/collectd-nut in pkgsrc speak), 
a time stamp from when the UPS sampled the data may be helpful in case of 
long delays (of which I don't know whether they happen) on the data's way 
to upsd.