#vulnerable code 
                                @CheckForNull
    @Override
    public CNode describe(T instance) throws Exception {

        // Here we assume a correctly designed DataBound Object will have required attributes set by DataBoundConstructor
        // and all others using DataBoundSetters. So constructor parameters for sure are part of the description, others
        // need to be compared with default values.

        // Build same object with only constructor parameters
        final Constructor constructor = getDataBoundConstructor(target);

        final Parameter[] parameters = constructor.getParameters();
        final String[] names = ClassDescriptor.loadParameterNames(constructor);
        final Attribute[] attributes = new Attribute[parameters.length];
        final Object[] args = new Object[parameters.length];
        for (int i = 0; i < parameters.length; i++) {
            final Parameter p = parameters[i];
            final Attribute a = detectActualType(names[i], p.getParameterizedType());
            args[i] = a.getValue(instance);
            attributes[i] = a;
        }

        T ref = (T) constructor.newInstance(args);

        // compare instance with this "default" object
        Mapping mapping = compare(instance, ref);

        // add constructor parameters
        for (int i = 0; i < parameters.length; i++) {
            final Configurator c = Configurator.lookup(attributes[i].getType());
            if (args[i] == null) continue;
            mapping.put(names[i], attributes[i].describe(args[i]));
        }

        return mapping;
    } 
                            #location 12 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @CheckForNull
    @Override
    public CNode describe(T instance) throws Exception {

        // Here we assume a correctly designed DataBound Object will have required attributes set by DataBoundConstructor
        // and all others using DataBoundSetters. So constructor parameters for sure are part of the description, others
        // need to be compared with default values.

        // Build same object with only constructor parameters
        final Constructor constructor = getDataBoundConstructor();

        final Parameter[] parameters = constructor.getParameters();
        final String[] names = ClassDescriptor.loadParameterNames(constructor);
        final Attribute[] attributes = new Attribute[parameters.length];
        final Object[] args = new Object[parameters.length];
        for (int i = 0; i < parameters.length; i++) {
            final Parameter p = parameters[i];
            final Attribute a = detectActualType(names[i], p.getParameterizedType());
            args[i] = a.getValue(instance);
            attributes[i] = a;
        }

        T ref = (T) constructor.newInstance(args);

        // compare instance with this "default" object
        Mapping mapping = compare(instance, ref);

        // add constructor parameters
        for (int i = 0; i < parameters.length; i++) {
            final Configurator c = Configurator.lookup(attributes[i].getType());
            if (args[i] == null) continue;
            mapping.put(names[i], attributes[i].describe(args[i]));
        }

        return mapping;
    }