Fix child routes not inheriting time interval configuration

[benridley]

Fixes #2833.

Fixes a bug in the creation of routes which would mistakenly override parent route config with empty time interval configuration if none were specified on the child.

[juliusv]

Thanks! I haven't checked in detail, but @simonpasquier mentioned in #2833 (comment) that overriding time intervals in children could lead to issues because empty time intervals are also valid. Would setting an explicit empty list of intervals (vs. omitting the field entirely) in a child allow overriding the time intervals of a parent with this PR?

[benridley]

Thanks! I haven't checked in detail, but @simonpasquier mentioned in #2833 (comment) that overriding time intervals in children could lead to issues because empty time intervals are also valid. Would setting an explicit empty list of intervals (vs. omitting the field entirely) in a child allow overriding the time intervals of a parent with this PR?

Maybe I'm misunderstanding the implications of this, but I think this shouldn't have any impact. Previously, every new route would receive an explicit empty list of intervals (through the DefaultRouteOpts struct) regardless of whether the parent had a set of time intervals or not. Now, child route will receive an empty list, or the parent's list if its not empty.

So empty time intervals on the parent will result in the same behaviour before this change. The change will be if the parent has defined intervals which will now be inherited.

[costela]

Friendly ping: the review seems to have fallen through the cracks? 😇