}

    /**
     * Creates a new messages instance for handling validation and user messages.
     * This method can be called by the application to create message containers.
     *
     * @return a new FessMessages instance
     */
    @Override
    public FessMessages createMessages() { // application may call

        return OptionalThing.of(asJson(createFailureBean(Status.BAD_REQUEST, createMessage(resource, cause))));
    }

    @Override
    public OptionalThing<ApiResponse> handleServerException(final ApiFailureResource resource, final Throwable cause) {
        return OptionalThing.of(asJson(createFailureBean(Status.SYSTEM_ERROR, createMessage(resource, cause))));
    }