private function loadUsersSettings()
    {
        if (null !== $this->usersSettings) {
            return;
        }

        $this->usersSettings = array_replace(
            self::$defaultUserSettings,
            // removes undefined keys in default settings
            array_intersect_key(
                $this->conf->get(['user-settings'], []),
                self::$defaultUserSettings
            )
        );
    }