code: private List<Collection<QueryResult>> lookupGPXEntries(List<Observation> gpxList,
                                                             EdgeFilter edgeFilter) {
  
          final List<Collection<QueryResult>> gpxEntryLocations = new ArrayList<>();
          for (Observation gpxEntry : gpxList) {
              final List<QueryResult> queryResults = locationIndex.findNClosest(
                      gpxEntry.getPoint().lat, gpxEntry.getPoint().lon, edgeFilter, measurementErrorSigma);
              gpxEntryLocations.add(queryResults);
          }
          return gpxEntryLocations;
      }
docs: Find the possible locations (edges) of each Observation in the graph.