protected function getElementClassString()
    {
        $elementClass = $this->getElementClass();

        if (Arr::isAssoc($elementClass)) {
            $classes = [];

            foreach ($elementClass as $index => $class) {
                $classes[$index] = is_array($class) ? implode(' ', $class) : $class;
            }

            return $classes;
        }

        return implode(' ', $elementClass);
    }