@GetMapping("/add")
    public String addGroup(Model model) {
        Group group = new Group();
        model.addAttribute(group);
        return "groups/show-group-form";
    }

@GetMapping("/update")
    public String updateGroup(Model model,@RequestParam("GroupId") Long Id ) {
        model.addAttribute("group",groupService.findById(Id));
        model.addAttribute("update", true);
        return "groups/show-group-form";
    }

@PostMapping("/processform")
    public String processForm(Model model,@ModelAttribute("Group") Group newGroup ) {
        groupService.add(newGroup);
        model.addAttribute("groups",groupService.getGroupsList());
        return "groups/list-groups";
    }