protected function renderChildrenInformation(NodeInterface $node, string $nodeTypeFilterString): array
    {
        $documentChildNodes = $node->getChildNodes($nodeTypeFilterString);
        // child nodes for content tree, must not include those nodes filtered out by `baseNodeType`
        $contentChildNodes = $node->getChildNodes($this->buildContentChildNodeFilterString());
        $childNodes = array_merge($documentChildNodes, $contentChildNodes);

        $mapper = function (NodeInterface $childNode) {
            return [
                'contextPath' => $childNode->getContextPath(),
                'nodeType' => $childNode->getNodeType()->getName() // TODO: DUPLICATED; should NOT be needed!!!
            ];
        };

        return array_map($mapper, $childNodes);
    }