protected function getContentTypeDomainMapper()
    {
        if ($this->contentTypeDomainMapper !== null) {
            return $this->contentTypeDomainMapper;
        }

        $this->contentTypeDomainMapper = new Helper\ContentTypeDomainMapper(
            $this->persistenceHandler->contentTypeHandler(),
            $this->persistenceHandler->contentLanguageHandler(),
            $this->getFieldTypeRegistry()
        );

        return $this->contentTypeDomainMapper;
    }