code: private static List<Vertex> addVertices(Collection<X509Certificate> certs,
                                              List<List<Vertex>> adjList)
      {
          List<Vertex> l = adjList.get(adjList.size() - 1);
  
          for (X509Certificate cert : certs) {
              Vertex v = new Vertex(cert);
              l.add(v);
          }
  
          return l;
      }
docs: /*
  Adds a collection of matching certificates to the
  adjacency list.