#vulnerable code 
                                public final void build() {
        LOGGER.info("Starting tree reconstruction");

        Project inbox = new Project();
        inbox.setName("Inbox");
        inbox.setId("__%%Inbox"); // to give deterministic JSON/XML output

        Context noContext = new Context();
        noContext.setName("No Context");
        noContext.setId("__%%NoContext"); // to give deterministic JSON/XML output

        // Build Folder Hierarchy
        for (Folder folder : folders.values()) {
            String parentId = folder.getParentFolderId();
            if (parentId != null) {
                Folder parent = folders.get(parentId);
                parent.add(folder);
            }
        }

        // Build Task Hierarchy
        for (Task task : tasks.values()) {
            String parentId = task.getParentTaskId();
            if (parentId != null) {
                Task parent = tasks.get(parentId);
                parent.add(task);
            }

            if (task.isInInbox() && task.getParentTaskId() == null) {
                inbox.add(task);
            }

            if (task.getContextId() == null) {
                noContext.add(task);
            }
        }

        // Build Context Hierarchy
        for (Context context : contexts.values()) {
            String parentId = context.getParentContextId();
            if (parentId != null) {
                Context parent = contexts.get(parentId);
                parent.add(context);
            }
        }

        // Add tasks to contexts
        for (Task task : tasks.values()) {
            String contextId = task.getContextId();
            if (contextId != null) {
                Context context = contexts.get(contextId);
                context.getTasks().add(task);
                task.setContext(context);
            }
        }

        // Create Projects from their root tasks
        // Must do this after task hierarchy is woven
        // since a copy of the root tasks subtasks is taken
        for (ProjectInfo projInfo : projInfos.values()) {
            Task rootTask = tasks.get(projInfo.getRootTaskId());
            Project project = new Project(projInfo, rootTask);

            // Set containing Folder for project
            String folderId = projInfo.getFolderId();
            if (folderId != null) {
                Folder folder = folders.get(folderId);
                folder.add(project);
            }

            projects.put(project.getId(), project);

            // Discard the root task. But note that it'll still be
            // a child in any contexts
            tasks.remove(rootTask.getId());
        }

        if (!inbox.getTasks().isEmpty()) {
            projects.put(inbox.getId(), inbox);
        }

        if (!noContext.getTasks().isEmpty()) {
            contexts.put(noContext.getId(), noContext);
        }

        LOGGER.info("Finished tree reconstruction");

    } 
                            #location 17 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public final void build() {
        LOGGER.info("Starting tree reconstruction");

        Project inbox = beanFactory.getBean("project", Project.class);
        inbox.setName("Inbox");
        inbox.setId("__%%Inbox"); // to give deterministic JSON/XML output

        Context noContext = beanFactory.getBean("context", Context.class);
        noContext.setName("No Context");
        noContext.setId("__%%NoContext"); // to give deterministic JSON/XML output

        ConfigParams configParams = beanFactory.getBean("configparams", ConfigParams.class);

        // Build Folder Hierarchy
        for (Folder folder : folders.values()) {
            String parentId = folder.getParentFolderId();
            if (parentId != null) {
                Folder parent = folders.get(parentId);
                parent.add(folder);
            }
        }

        // Build Task Hierarchy
        for (Task task : tasks.values()) {
            String parentId = task.getParentTaskId();
            if (parentId != null) {
                Task parent = tasks.get(parentId);
                parent.add(task);
            }

            if (task.isInInbox() && task.getParentTaskId() == null) {
                inbox.add(task);
            }

            if (task.getContextId() == null) {
                noContext.add(task);
            }
        }

        // Build Context Hierarchy
        for (Context context : contexts.values()) {
            String parentId = context.getParentContextId();
            if (parentId != null) {
                Context parent = contexts.get(parentId);
                parent.add(context);
            }
        }

        // Add tasks to contexts
        for (Task task : tasks.values()) {
            String contextId = task.getContextId();
            if (contextId != null) {
                Context context = contexts.get(contextId);
                context.getTasks().add(task);
                task.setContext(context);
            }
        }

        // Create Projects from their root tasks
        // Must do this after task hierarchy is woven
        // since a copy of the root tasks subtasks is taken
        for (ProjectInfo projInfo : projInfos.values()) {
            Task rootTask = tasks.get(projInfo.getRootTaskId());
            Project project = new Project(projInfo, rootTask);
            project.setConfigParams(configParams);

            // Set containing Folder for project
            String folderId = projInfo.getFolderId();
            if (folderId != null) {
                Folder folder = folders.get(folderId);
                folder.add(project);
            }

            projects.put(project.getId(), project);

            // Discard the root task. But note that it'll still be
            // a child in any contexts
            tasks.remove(rootTask.getId());
        }

        if (!inbox.getTasks().isEmpty()) {
            projects.put(inbox.getId(), inbox);
        }

        if (!noContext.getTasks().isEmpty()) {
            contexts.put(noContext.getId(), noContext);
        }

        LOGGER.info("Finished tree reconstruction");

    }