[Flow] Achieve loose coupling between packages (models)

[Teo C.]

Thank you Søren, I think you are referring to this part of the manual, am I correct ?

http://docs.typo3.org/flow/TYPO3FlowDocumentation/TheDefinitiveGuide/PartIII/ObjectManagement.html#overriding-object-implementations

I tried but I don't seem to make it work, the problem I think is because the injection is within a doctrine ManyToMany Relationship.

Here it is the declaration of the relation within the main package
/**
* @var \Doctrine\Common\Collections\Collection<\Booking\Domain\Model\BookingParticipantInterface>
* @ORM\ManyToMany
* @Flow\Inject
*/
protected $participants; 

And here the Objects.yaml file:

Booking\Domain\Model\BookingParticipantInterface:
  className: 'User\Domain\Model\Person'

The "Person" class implements BookingParticipantInterface.

I always get this error on docrtrine:update:

No class schema found for
  "Booking\Domain\Model\BookingParticipantInterface". The class should
  probably marked as entity or value object! 

It seems the substitution is not performed :-(

Any hint on what could be the problem ? Thanks !