I've done some work on arc routing problems in the past (the Chinese postman problem is an arc routing problem). Although bits of Graphhopper and jsprit could be useful to you, jsprit itself isn't really setup for arc routing. Jsprit does node routing - where you're visiting individual locations. Instead you're visiting road arcs - so you have to consider things like traversal direction etc. Jsprit could be extended to do arc routing, but I suspect the amount of development involved would probably be similar (or maybe more) than writing a Chinese postman problem solver from scratch.