[4.0] Multililanguage: Associations do not display any more for articles categories

[infograf768]

Steps to reproduce the issue

Install last 4.0-dev
Enable the Language filter plugin and make sure Associations is set to Yes.
Display Articles Categories Manager
or edit an Article Category

Expected result

In the manager, the Associations column should display
When editing a category, the Associations tab should display

Actual result

Both don't display.
$this->assoc is always false

[infograf768]

I think I found the issue:
The code for getAssoc() method is looking for helpers the old way, i.e.

		else
		{
			$hname = $cname . 'HelperAssociation';
			\JLoader::register($hname, JPATH_SITE . '/components/' . $component . '/helpers/association.php');

			$assoc = class_exists($hname) && !empty($hname::$category_association);
		}

		return $assoc;

but not only the helpers folder does not exist anymore for com_content as it is now
/Helper/AssociationsHelper.php
but also the class has no more component name
i.e. it is class AssociationsHelper extends \CategoryHelperAssociation
instead of
abstract class ContentHelperAssociation extends CategoryHelperAssociation

This explains why it still work for com_contact but not for com_content...
Briefly said, it's all broken...

[laoneo]

Please test #20692 which should fix the issue.