if (fromVertex == null)
{
fromVertex = new DeterministicDirectedSparseGraph.DeterministicVertex();
if (existingVertices.isEmpty())
fromVertex.addUserDatum(JUConstants.PROPERTY, JUConstants.INIT, UserData.SHARED);
fromVertex.addUserDatum(JUConstants.ACCEPTED, "true", UserData.SHARED);
fromVertex.addUserDatum(JUConstants.LABEL, from, UserData.SHARED);
existingVertices.put(from, fromVertex);
g.addVertex(fromVertex);
}