TransitStop stopVertex = (TransitStop) context.stationStopNodes.get(stop);
String agencyId = stop.getId().getAgencyId();
AgencyAndId parentStationId = new AgencyAndId(agencyId, parentStation);
Stop parentStop = _dao.getStopForId(parentStationId);
if(context.stationStopNodes.get(parentStop) instanceof TransitStation) {
TransitStation parentStopVertex = (TransitStation)
context.stationStopNodes.get(parentStop);
new StationStopEdge(parentStopVertex, stopVertex);
new StationStopEdge(stopVertex, parentStopVertex);
} else {
LOG.warn(graph.addBuilderAnnotation(new NonStationParentStation(stopVertex)));