[Flow] Question about extending model

[Winfried Mingst]

Hi,
I tried to extend the model of class \TYPO3\Media\Domain\Model\Image by 
some additional properies.
doctrine:update creates  my new table "File". But the resource property, 
a foreign key to typo3_resource_resouce is not created. No matter if I 
define it in class File or not.
What I'm doing wrong?


/**
  * A File
  *

  * @Flow\Scope("prototype")
  * @Flow\Entity

  */
class File extends \TYPO3\Media\Domain\Model\Image {

/**
protected myproperty1
*/
....