Problem description
Copied (only the conclusion after discussion) from camaraproject/DeviceStatus#138

lastStatusTime is an optional parameter in the 200 responses of the status APIs. But there is no good reason not to include this parameter. Otherwise, there is the risk of ambiguity as to whether the returned status is still valid. It should be mandatory for any status that is not current, and the simplest way to enforce that is to make it mandatory for all responses.

Possible evolution
lastStatusTime mandatory in 200 responses of the status API

Alternative solution

Additional context