Config entity types MUST allow NULL value for any config entity PHP class property corresponding to config entity property

… or … on second thought … should we flip that around, and is this not a bug in this test, but in the config entity infrastructure, where every config entity type MUST allow NULL to be set on any class property corresponding to a top-level config entity property, precisely to avoid triggering fatal PHP errors for something as innocent as:

$format = FilterFormat::load('basic_html');
$format->set('settings', NULL);

Wim Leers → credited f.mazeikis → .

So if "every config entity type MUST allow NULL to be set on any class property corresponding to a top-level config entity property" would the implication be that:

  protected array $settings = [];

Gets interpreted as:

  protected array|null $settings = [];

That seems confusing to me.

Change appears to have caused a test failure.

I'm pretty sure the intention of the change (with the commit message "Example") was to demonstrate a test failure.