#vulnerable code 
                                private void paginatedbroadcastQueryTasksOnExampleStates () throws Throwable {

        VerificationHost targetHost = this.host.getPeerHost();
        URI exampleFactoryURI = UriUtils.buildUri(targetHost, ExampleFactoryService.SELF_LINK);

        int serviceCount = 100;
        int resultLimit = 30;
        this.host.testStart(serviceCount);
        List<URI> exampleServices = new ArrayList<>();
        for (int i = 0; i < serviceCount; i++) {
            ExampleServiceState s = new ExampleServiceState();
            s.name = "document" + i;
            s.documentSelfLink = s.name;

            exampleServices.add(UriUtils.buildUri(this.host.getUri(),
                    ExampleFactoryService.SELF_LINK, s.documentSelfLink));

            this.host.send(Operation.createPost(exampleFactoryURI)
                    .setBody(s)
                    .setCompletion(this.host.getCompletion()));
        }
        this.host.testWait();

        QuerySpecification q = new QuerySpecification();
        Query kindClause = new Query();
        kindClause.setTermPropertyName(ServiceDocument.FIELD_NAME_KIND)
                .setTermMatchValue(Utils.buildKind(ExampleServiceState.class));
        q.query = kindClause;
        q.options = EnumSet.of(QueryOption.EXPAND_CONTENT, QueryOption.BROADCAST);
        q.resultLimit = resultLimit;

        QueryTask task = QueryTask.create(q);

        URI taskUri = this.host.createQueryTaskService(task, false, task.taskInfo.isDirect, task, null);
        task = this.host.waitForQueryTaskCompletion(task.querySpec, 0, 0, taskUri, false, false);

        targetHost.testStart(1);
        Operation startGet = Operation
                .createGet(taskUri)
                .setCompletion((o, e) -> {
                    if (e != null) {
                        targetHost.failIteration(e);
                        return;
                    }

                    QueryTask rsp = o.getBody(QueryTask.class);
                    assertTrue(0 == rsp.results.documentCount);
                    assertTrue(rsp.results.nextPageLink.contains(UriUtils.buildUriPath(ServiceUriPaths.CORE,
                            BroadcastQueryPageService.SELF_LINK_PREFIX)));

                    targetHost.completeIteration();
                });
        targetHost.send(startGet);
        targetHost.testWait();

        String nextPageLink = task.results.nextPageLink;
        Set<String> documentLinks = new HashSet<>();
        while (nextPageLink != null) {
            List<String> pageLinks = new ArrayList<>();
            URI u = UriUtils.buildUri(targetHost, nextPageLink);

            targetHost.testStart(1);
            Operation get = Operation
                    .createGet(u)
                    .setCompletion((o, e) -> {
                        if (e != null) {
                            targetHost.failIteration(e);
                            return;
                        }

                        QueryTask rsp = o.getBody(QueryTask.class);
                        pageLinks.add(rsp.results.nextPageLink);
                        documentLinks.addAll(rsp.results.documentLinks);

                        targetHost.completeIteration();
                    });

            targetHost.send(get);
            targetHost.testWait();

            nextPageLink = pageLinks.isEmpty() ? null : pageLinks.get(0);
        }

        assertEquals(serviceCount, documentLinks.size());

        for (int i = 0; i < serviceCount; i++) {
            assertTrue(documentLinks.contains(ExampleFactoryService.SELF_LINK + "/document" + i));
        }
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private void paginatedbroadcastQueryTasksOnExampleStates () throws Throwable {

        VerificationHost targetHost = this.host.getPeerHost();

        int serviceCount = 100;
        int resultLimit = 30;

        QuerySpecification q = new QuerySpecification();
        Query kindClause = new Query();
        kindClause.setTermPropertyName(ServiceDocument.FIELD_NAME_KIND)
                .setTermMatchValue(Utils.buildKind(ExampleServiceState.class));
        q.query = kindClause;
        q.options = EnumSet.of(QueryOption.EXPAND_CONTENT, QueryOption.BROADCAST);
        q.resultLimit = resultLimit;

        QueryTask task = QueryTask.create(q);

        URI taskUri = this.host.createQueryTaskService(task, false, task.taskInfo.isDirect, task, null);
        task = this.host.waitForQueryTaskCompletion(task.querySpec, 0, 0, taskUri, false, false);

        targetHost.testStart(1);
        Operation startGet = Operation
                .createGet(taskUri)
                .setCompletion((o, e) -> {
                    if (e != null) {
                        targetHost.failIteration(e);
                        return;
                    }

                    QueryTask rsp = o.getBody(QueryTask.class);
                    assertTrue(0 == rsp.results.documentCount);
                    assertTrue(rsp.results.nextPageLink.contains(UriUtils.buildUriPath(ServiceUriPaths.CORE,
                            BroadcastQueryPageService.SELF_LINK_PREFIX)));

                    targetHost.completeIteration();
                });
        targetHost.send(startGet);
        targetHost.testWait();

        String nextPageLink = task.results.nextPageLink;
        Set<String> documentLinks = new HashSet<>();
        while (nextPageLink != null) {
            List<String> pageLinks = new ArrayList<>();
            URI u = UriUtils.buildUri(targetHost, nextPageLink);

            targetHost.testStart(1);
            Operation get = Operation
                    .createGet(u)
                    .setCompletion((o, e) -> {
                        if (e != null) {
                            targetHost.failIteration(e);
                            return;
                        }

                        QueryTask rsp = o.getBody(QueryTask.class);
                        pageLinks.add(rsp.results.nextPageLink);
                        documentLinks.addAll(rsp.results.documentLinks);

                        targetHost.completeIteration();
                    });

            targetHost.send(get);
            targetHost.testWait();

            nextPageLink = pageLinks.isEmpty() ? null : pageLinks.get(0);
        }

        assertEquals(serviceCount, documentLinks.size());

        for (int i = 0; i < serviceCount; i++) {
            assertTrue(documentLinks.contains(ExampleFactoryService.SELF_LINK + "/document" + i));
        }
    }