#vulnerable code 
                                @Override public ArrayList<Constraint> decompose(Store store) {

        if (constraints != null)
            return constraints;

        IntDomain setComplement = new IntervalDomain();
        for (IntVar var : list)
            setComplement.addDom(var.domain);
        setComplement = setComplement.subtract(set);

        FSM fsm = new FSM();

        fsm.initState = new FSMState();
        fsm.allStates.add(fsm.initState);

        HashMap<FSMState, Integer> mappingQuantity = new HashMap<FSMState, Integer>();
        HashMap<String, FSMState> mappingString = new HashMap<String, FSMState>();

        mappingQuantity.put(fsm.initState, 0);
        mappingString.put("", fsm.initState);

        for (int i = 0; i < q; i++) {
            HashMap<String, FSMState> mappingStringNext = new HashMap<String, FSMState>();

            for (Map.Entry<String, FSMState> entry : mappingString.entrySet()) {
                String stateString = entry.getKey();
                FSMState state = entry.getValue();

                if (mappingQuantity.get(state) < max) {
                    // transition 1 (within a set) is allowed
                    FSMState nextState = new FSMState();
                    state.addTransition(new FSMTransition(set, nextState));
                    mappingStringNext.put(stateString + "1", nextState);
                    mappingQuantity.put(nextState, mappingQuantity.get(state) + 1);
                }

                if (mappingQuantity.get(state) + (q - i) > min) {
                    // transition 0 (outside set) is allowed
                    FSMState nextState = new FSMState();
                    state.addTransition(new FSMTransition(setComplement, nextState));
                    mappingStringNext.put(stateString + "0", nextState);
                    mappingQuantity.put(nextState, mappingQuantity.get(state));
                }
            }

            fsm.allStates.addAll(mappingString.values());
            mappingString = mappingStringNext;

        }

        fsm.allStates.addAll(mappingString.values());
        fsm.finalStates.addAll(mappingString.values());

        for (String description : mappingString.keySet()) {

            String one = description.substring(1) + "1";

            FSMState predecessor = mappingString.get(description);
            FSMState successor = mappingString.get(one);
            if (successor != null)
                predecessor.addTransition(new FSMTransition(set, successor));

            String zero = description.substring(1) + "0";
            successor = mappingString.get(zero);
            if (successor != null)
                predecessor.addTransition(new FSMTransition(setComplement, successor));
        }

        fsm.resize();

        constraints = new ArrayList<Constraint>();
        constraints.add(new Regular(fsm, list));

        return constraints;
    } 
                            #location 66 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override public ArrayList<Constraint> decompose(Store store) {

        if (constraints != null)
            return constraints;

        IntDomain setComplement = new IntervalDomain();
        for (IntVar var : list)
            setComplement.addDom(var.domain);
        setComplement = setComplement.subtract(set);

        FSM fsm = new FSM();

        fsm.initState = new FSMState();
        fsm.allStates.add(fsm.initState);

        HashMap<FSMState, Integer> mappingQuantity = new HashMap<FSMState, Integer>();
        HashMap<String, FSMState> mappingString = new HashMap<String, FSMState>();

        mappingQuantity.put(fsm.initState, 0);
        mappingString.put("", fsm.initState);

        for (int i = 0; i < q; i++) {
            HashMap<String, FSMState> mappingStringNext = new HashMap<String, FSMState>();

            for (Map.Entry<String, FSMState> entry : mappingString.entrySet()) {
                String stateString = entry.getKey();
                FSMState state = entry.getValue();

                if (mappingQuantity.get(state) < max) {
                    // transition 1 (within a set) is allowed
                    FSMState nextState = new FSMState();
                    state.addTransition(new FSMTransition(set, nextState));
                    mappingStringNext.put(stateString + "1", nextState);
                    mappingQuantity.put(nextState, mappingQuantity.get(state) + 1);
                }

                if (mappingQuantity.get(state) + (q - i) > min) {
                    // transition 0 (outside set) is allowed
                    FSMState nextState = new FSMState();
                    state.addTransition(new FSMTransition(setComplement, nextState));
                    mappingStringNext.put(stateString + "0", nextState);
                    mappingQuantity.put(nextState, mappingQuantity.get(state));
                }
            }

            fsm.allStates.addAll(mappingString.values());
            mappingString = mappingStringNext;

        }

        fsm.allStates.addAll(mappingString.values());
        fsm.finalStates.addAll(mappingString.values());

        for (Map.Entry<String, FSMState> entry : mappingString.entrySet()) {
            String description = entry.getKey();
            FSMState state = entry.getValue();

            String one = description.substring(1) + "1";

            FSMState predecessor = state;
            FSMState successor = mappingString.get(one);
            if (successor != null)
                predecessor.addTransition(new FSMTransition(set, successor));

            String zero = description.substring(1) + "0";
            successor = mappingString.get(zero);
            if (successor != null)
                predecessor.addTransition(new FSMTransition(setComplement, successor));
        }

        fsm.resize();

        constraints = new ArrayList<Constraint>();
        constraints.add(new Regular(fsm, list));

        return constraints;
    }