Контроллер:
    @PostMapping
    public String postObjects(@Valid ThatObject obj, Errors errors, SessionStatus sessionStatus) {
        if (errors.hasErrors()) {
            log.info("Errors: {}", errors.toString());
            return "thatobject";
        }
        log.info(obj.toString() + " add object111!!!!" + errors.toString());
        objectRep.save(obj);
        sessionStatus.setComplete();
        return "redirect:/";
    }

Форма:
<form method="POST" th:object="${thatobject}">

                <div th:if="${#fields.hasErrors()}">
                    <span class="validationError">
                        Please correct the problems below and resubmit.
                    </span>
                </div>
                <td>
                    <input type="text" th:field="*{nameObject}" id="name" placeholder="Название объекта"/>
                    <span class="validationError" th:if="${#fields.hasErrors('nameObject')}"
                        th:errors="*{nameObject}">Too short name</span>

                </td>
                <td>
                    <input type="text" th:field="*{adressObject}" id="adr" placeholder="Адрес"/>
                    <span class="validationError" th:if="${#fields.hasErrors('adressObject')}"
                        th:errors="*{adressObject}">Short</span>
                </td>
                <td>
                    <input type="text" th:field="*{commentAboutObject}" id="comment" placeholder="Комментарий"/>
                    <input type="submit" value="добавить объект">
                </td>

            </form>