ElasticsearchPostController.java

    @RequestMapping(value = "/{id}")
    @ApiOperation(value = "Returns a post by id")
    public Map<String, Optional<ElasticsearchPost>> findById(@PathVariable("id") long id) {

        Optional<ElasticsearchPost> elasticsearchPost = elasticsearchPostRepository.findById(id);
        Map<String, Optional<ElasticsearchPost>> elasticsearchPostMap = new HashMap<>();
        elasticsearchPostMap.put("ElasticsearchPosts", elasticsearchPost);

        return elasticsearchPostMap;
    }