Zend\Stdlib\Hydrator interfaces no longer accepted by Zend\Form #25
Description
I happened to do a "composer update" on one of my projects very soon after Zend\Form 2.6.0 was released, and because of my version constraint (~2.5) it was installed...and then my form broke with this error:
Argument 1 passed to Zend\Form\Fieldset::setHydrator() must implement interface Zend\Hydrator\HydratorInterface, instance of ******\UserQueryHydrator given
Since my custom hydrator implemented the Zend\Stdlib\Hydrator\HydratorInterface directly instead of inheriting from AbstractHydrator I could no longer use my custom hydrator in forms.
The fix was simple (replace references to "Stdlib\Hydrator" with "Hydrator") but it's still a break. IMO the better way to fix it would be to update the interfaces in Zend\Stdlib\Hydrator to extend the new ones from the Zend\Hydrator namespace. If that's an acceptable solution I can send a PR