GraphHopper API test

Not sure if that exists. Maybe graphHopper.getLocationIndex().findClosest(double, double, EdgeFilter).

Heuristics approach

Data set cannot be loaded if it contains at least one unreachable location. In that case the menu item for this data set should be disabled.

Typical case is that all locations of a data set are outside the OSM or inside it.

Corner case 1: Subset of locations are unreachable from the other ones because the data set was created on Europe OSM and spans multiple countries (e.g. Benelux) and currently loaded OSM is just one of the countries (Belgium). => disabled

Corner case 2: One location becomes unreachable after updating the OSM (change in road network). It should be possible to import the data set.

Keep relationship between a data set and an OSM

Downside: unless we also know hierarchy between OSM it could be impossible to import a Boston data set with Massachusetts OSM loaded.