private function computeElements(array $sourceElements, array $draftElements)
    {
        $elements = [];
        if ($this->getContent() instanceof ContentSet) {
            $elements = [
                'current' => $sourceElements,
                'draft'   => $draftElements,
            ];
        } else {
            foreach ($sourceElements as $key => $element) {
                if ($element !== $draftElements[$key]) {
                    $elements[$key] = [
                        'current' => $element,
                        'draft'   => $draftElements[$key],
                    ];
                }
            }
        }

        return $elements;
    }