make:entity setter for non nullable fields must allow null values to allow validating

This is closely related to #198.

As @javiereguiluz comments, all setters - even for nullable fields - must allow null values to be passed in order for the validation to work. At the moment:

   /**
     * @ORM\Column(type="integer", nullable=false)
     * @Assert\NotNull()
     */
    private $adpointPublicationId;

generates:

    public function setAdpointPublicationId(int $adpointPublicationId): self
    {
        $this->adpointPublicationId = $adpointPublicationId;

        return $this;
    }

so when null values passed through a form, we get the following error before validation is done.

Argument 1 passed to App\Entity\Product::setAdpointSectionGroupId() must be of the type integer, null given, called in .../backend/vendor/symfony/property-access/PropertyAccessor.php on line 527
Exception

Thanks, Hannes

Start with the make:entity command's setter generation and review the behavior described in related issue #198. Reproduce the example with a non-nullable field receiving null through a form; done means the generated setter accepts null so validation can run before the type error.