code: public static RouteSpecification forCargo(Cargo cargo, DateTime arrivalDeadline) {
        Validate.notNull(cargo);
        Validate.notNull(arrivalDeadline);
  
        return new RouteSpecification(arrivalDeadline, cargo.getOrigin(), cargo.getDestination());
      }
docs: Factory for creatig a route specification for a cargo, from cargo
  origin to cargo destination. Use for initial routing.
  
  @param cargo cargo
  @param arrivalDeadline arrival deadline
  @return A route specification for this cargo and arrival deadline