code: public List<Link> getStaticRoute(NodesMap nm) {
  
          Map<Link, Boolean> route = routes.get(nm);
  
          if (route == null) {
              return null;
          }
  
          return new ArrayList<>(route.keySet());
      }
docs: Get the static route between two given nodes.
  
  @param nm    the nodes map
  @return the static route. {@code null} if not found