TYPO3.Media

I want to remove an Image Entity from another Entity by its Identity.
So i used <f:link.action action="remove" arguments={section:section,image:image}> ...
The resulting URI looks like this: &section[__identity]=29870197-33ca-43c7-9649-70c3c0f28004&image[__identity]=51e35272-e273-4aa3-8f3f-bdd0932edb23

• Remove Image from a given Section
• @param \My\Name\Domain\Model\Section $section
• @param \TYPO3\Media\Domain\Model\Image $image
• @return void
  */
  public function removeImageAction(\My\Name\Domain\Model\Section $section, \TYPO3\Media\Domain\Model\Image $image){
  $section->removeImage($image);
  $this->persistenceManager->update($section);
  $this->redirect('show',NULL,NULL,array('section'=>$section));
  }

But the mapping throws the following exception for this removeImageAction:
#1297759968: Exception while property mapping for target type "TYPO3\Media\Domain\Model\Image", at property path "": It is not allowed to map property "__identity". You need to use $propertyMappingConfiguration->allowProperties('__identity') to enable mapping of this property. (More information)

Just for testing i disabled the mathing of the ImageConverter from $targetType = 'TYPO3\Media\Domain\Model\Image';
to $targetType = 'TYPO3\Media\Domain\Model\ImageFoo';

And the mapping works again.
Can somebody explain me the need of this ImageConverter?

Kind regards
Carsten