`/agendas/-/items` seems needlessly complicated, but there is a reason for that:
In REST, it is common to specify paths of the form `/{type}/<id>`. If `{type}` is a composite, i.e., consists of instances of a `{subtype}`, REST recommends a path of the form `/{type}/<id>/{subtype}/<id>` to address a particular instance of the subtype. For endpoints that return all instances of a particular type, `/{type}` is used. In case of composite instances, `/{type}/<id>/{subtype}` is used.
It felt wrong just to use `/items` to get all agenda items, as items is very unspecific. `/agenda-items` would have been possible, but a bit ugly. We therefore opted to model items as composites of an agenda, leaving us with `/agendas/<id>/items` as path to get all items.
