public function renderHiddenSpoiler()
    {
        $options = ArrayHelper::merge([
            'id' => $this->button['id'] . '-body',
            'tag' => 'span',
            'value' => implode($this->hiddenDelimiter ?? $this->delimiter, $this->getSpoiledItems()),
            'class' => 'collapse',
            'data-spoiler-body' => true,
        ], $this->hidden);

        $this->parts['{hidden}'] = Html::tag(ArrayHelper::remove($options, 'tag'), ArrayHelper::remove($options, 'value'), $options);
    }