Hi Simon, I am also facing this issue, here Raymond have used ConcurrentHashMap to resolve the issue as mentioned in TUSCANY-2069, but we can't be using ConcurrentHashMap in this case as this collection (ConcurrentHashMap) does not allow null value to be inserted in the Map. Since the DirectedGraph.java class explicitly tries to insert null value in its getShortestPath() method we see this exception. For now we can revert to the old code of having HashMap to resolve this issue.
-- Thanks & Regards, Ramkumar Ramalingam
