Own modules tables changed after Prestahop upgrade. DEFAULT NULL to NOT NULL

[Gneston]

Hi, 

I recently upgraded to Prestashop 1.7.8.5 from Prestahop 1.7.6.1.

I have some self written modules where I use Doctrine to store my data in the database (like its explained here: https://devdocs.prestashop.com/1.7/modules/concepts/doctrine/) 

I created the databases with an sql script like this one: 

And in src/Entity I have a File called MpOrder.php where I wrote this: 

After the Prestashop upgrade the ps_mp_order was changed and id_shipment was not longer allowed to be nullable. I manually changed the table definition, so my modules works again, but why did this occur? I have a database dump from before the upgrade and the field is described there with 

After the upgrade a dump of the same table showed 

So I am quite sure, the upgrade changed something here. What have I done wrong? What do I have to do, to prevent the next Prestashop upgrade from changing my nullable fields to not nullable fields?

Edit: I can not write code blocks here. The website tells me my request have been blocked, when I click on submit/edit after inserting code in code blocks. That's why I use images instead.

Edited April 26, 2022 by Gneston
Adding code as images (see edit history)