gistfile1.txt

   @RequestMapping(
            path = "/api/groups",
            method =  RequestMethod.GET)
    public @ResponseBody List<StudentsGroup> getGroups() {
        List<StudentsGroup> result = new ArrayList<>();
        try {
            mGroupsRepository.findAll().forEach(result::add);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }