#vulnerable code 
                                @Test
    public void skillViolationAtAct2_shouldWork(){
        SolutionAnalyser analyser = new SolutionAnalyser(vrp,solution, new SolutionAnalyser.DistanceCalculator() {
            @Override
            public double getDistance(String fromLocationId, String toLocationId) {
                return vrp.getTransportCosts().getTransportCost(fromLocationId,toLocationId,0.,null,null);
            }
        });
        VehicleRoute route = solution.getRoutes().iterator().next();
        Boolean violated = analyser.skillConstraintIsViolatedAtActivity(route.getActivities().get(1),route);
        assertTrue(violated);
    } 
                            #location 11 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void skillViolationAtAct2_shouldWork(){
        SolutionAnalyser analyser = new SolutionAnalyser(vrp,solution, new SolutionAnalyser.DistanceCalculator() {
            @Override
            public double getDistance(String fromLocationId, String toLocationId) {
                return vrp.getTransportCosts().getTransportCost(fromLocationId,toLocationId,0.,null,null);
            }
        });
        VehicleRoute route = solution.getRoutes().iterator().next();
        Boolean violated = analyser.hasSkillConstraintViolationAtActivity(route.getActivities().get(1), route);
        assertTrue(violated);
    }