The Time sent with a sample should be: time stamp at which the value was collected.
Currently there are 2 scenarios as regards time stamps with samples:

1. Where the subsystem we are reading from CAN provide us with the “incident” time (time at which an event occurred) and the collector can provide us with the collection time (time at which a sample was collected): In this case we have the “incident” time for the sample/event and the time when a collector retrieves the sample...

2. where the subsystem we are reading from CANNOT provide us with the “incident” time only the collection time: In this case we only have the time for when the collector retrieves the sample.

The recommendation for collectors where possible is to collect both incident time and collection time and send them with a sample.

For collectd there is only 1 time stamp field. The recommendation is to send the collection time in the collectd time stamp field for values and notifications- BUT where detection time is available to send it in the metadata.

The idea behind this story is to ensure that all plugins to date don't set the collector timestamp - but let collectd do it and where they do set the timestamp - that it's put into the metadata.

Must validate that this is the case for all barometer plugins