Set hydrator recursive

gistfile1.php

public class someForm extends Form {
    public function setHydrator(\Zend\Stdlib\Hydrator\HydratorInterface $hydrator) {
        parent::setHydrator($hydrator);
        $this->setHydratorRecursive($hydrator, $this);
    }

    protected function setHydratorRecursive($hydrator, $fieldset) {
        $nextfieldsets = $fieldset->getFieldsets();
        foreach ($nextfieldsets as $nextfieldset) {
            $nextfieldset->setHydrator($hydrator);
            $this->setHydratorRecursive($hydrator, $nextfieldset);
        }
    }
}