public function initializeCreateAction() {
        /** @var $propertyMappingConfiguration \TYPO3\FLOW3\Mvc\Controller\MvcPropertyMappingConfiguration */
        $propertyMappingConfiguration = $this->arguments['newTopic']->getPropertyMappingConfiguration();

        $propertyMappingConfiguration->allowCreationForSubProperty('image');

        $propertyMappingConfiguration->getConfigurationFor('image')->allowProperties('title');

        $propertyMappingConfiguration->getConfigurationFor('image.title')
            ->setTypeConverterOption('TYPO3\FLOW3\Property\TypeConverter\PersistentObjectConverter', \TYPO3\FLOW3\Property\TypeConverter\PersistentObjectConverter::CONFIGURATION_TARGET_TYPE, 'string');
    }