D-Net

    @RequestMapping(value = "/{stakeholderId}/{topicId}/reorder", method = RequestMethod.POST)

    public List<Category> reorderCategories(@PathVariable("stakeholderId") String stakeholderId,

                                             @PathVariable("topicId") String topicId,

                                             @RequestBody List<String> categories) {

        log.debug("reorder categories");

        log.debug("Stakeholder: "+stakeholderId + " - Topic: "+topicId);

        Topic<String> topic = checkForExceptions(stakeholderId, topicId);

        topic.setCategories(categories);

        topicDAO.save(topic);

        log.debug("Categories reordered!");

        List<Category> categoriesFull = new ArrayList<>();

        for(String categoryId : categories) {

            categoriesFull.add(categoryDAO.findById(categoryId));

        }

        return categoriesFull;

    }

    private Topic checkForExceptions(String stakeholderId, String topicId) {

        Stakeholder<String> stakeholder = stakeholderDAO.findById(stakeholderId);

        if(stakeholder == null) {

            // EXCEPTION - Stakeholder not found

            throw new EntityNotFoundException("checkForExceptions category: Stakeholder with id: " + stakeholderId + " not found");

        }

        Topic<String> topic = topicDAO.findById(topicId);

        if(topic == null) {

            // EXCEPTION - Topic not found

            throw new EntityNotFoundException("checkForExceptions category: Topic with id: "+topicId+" not found");

        }

        if(!stakeholder.getTopics().contains(topicId)) {

            // EXCEPTION - Topic not found in Stakeholder: stakeholder.getAlias();

            throw new PathNotValidException("checkForExceptions category: Topic with id: "+topicId+" not found in Stakeholder: "+stakeholderId);

        }

        return  topic;

    }