private function parseMappingFields(\DOMXPath $xpath, \DOMNode $typeRootNode)
    {
        $fields = [];
        $fieldSearchPath = sprintf('%s/%s', self::MAPPING_NODE_TYPE, self::MAPPING_FIELD_NODE_TYPE);

        foreach ($xpath->query($fieldSearchPath, $typeRootNode) as $fieldNode) {
            $fields[$fieldNode->getAttribute('name')] = $this->createMappingField($fieldNode);
        }

        return $fields;
    }