class OspfTopology {

  @Nonnull
  public Set<EdgeId> incomingEdges(OspfNeighborConfigId head) {
    if (!_graph.nodes().contains(head)) {
      return ImmutableSet.of();
    }
    return _graph.predecessors(head).stream()
        .map(tail -> makeEdge(tail, head))
        .collect(ImmutableSet.toImmutableSet());
  }

  public  OspfTopology(ValueGraph<OspfNeighborConfigId, OspfSessionProperties> graph);

}