src/Entity/Hydrator/ImageSetHydrator.php
public function extract($object)
    {
        if (!$object instanceof ImageSet || !($image = $object->get(ImageSetInterface::ORIGINAL))) {
            return [];
        }

        return [$this->options->getFormElementName() => $image->getId()];
    }
public function extract($object)
    {
        if (!$object instanceof ImageSet || !($image = $object->get(ImageSetInterface::ORIGINAL))) {
            return [];
        }

        return [$this->options->getFormElementName() => $image->getId()];
    }
Extract values from an object

@param object $object

@return array