Liferay 7 Eclipse IDE override default categories

Question

I’m looking for a way to override the default category filter behaviour for Asset Publisher widgets (point 3 of my previous question here).
As far as I understand in the Setup > Asset Section > Filter a rule based on categories will look for all source > asset type components which match the selected categories.
I would like to know where is default query stored and how it is possible to modify it in order to introduce other custom criteria.

Update:
I can create a Liferay module project fragment, but I wasn't able to retrieve the correct OSGi bundle and relative file to override the default query filter behaviour.