REST API doesn't update Last-Modified or ETag on state change

If a resource in MaxScale is modified due to internal events (e.g. statistics being updated) the ETag and Last-Modified values aren't updated. The update only happens if a user modifies the resource. This causes various web frameworks to return stale data even though the data has changed.

Calculating a checksum or a hash and using that as the ETag would make it possible to detect updates that happen internally. By comparing this ETag the Last-Modified could also be updated. The downside is that the request would always be executed and the result discarded if the resource hasn't changed.