Media Library widget in a custom_field are not working as expected

Problem/Motivation

I'm facing an issue with a paragraph using a field created withthe contrib module custom_field ( https://www.drupal.org/project/custom_field → ). The Media Library widget provided for Media entity reference is working OK used in a regular paragraph (stable) widget, but when used with layout paragraphs, the referenced media ids are always empty.

Steps to reproduce

To avoid duplication, here is the initial issue opened against custom_field contrin module : https://www.drupal.org/project/custom_field/issues/3511543 🐛 Media library widget not working with Layout paragraphs Active

It seems that layout paragraphs is not creating the subforms the same way as the regular paragraph widget does, making the form parents key being empty, and in consequence making the widget to be unusable.

Proposed resolution

As mentioned in the custom_field contrib issue queue link above, I managed to workaround by creating a custom widget to fit the needs using the custom_field widget base. But as this module is really usefull, making possible to create groups of fields as part of a normal paragraph field (and avoiding creation of sub paragraph types just for that purpose) I think it could be a great benefit to integrate that custom_field field type to layout paragraphs architecture.

Unfortunately, i'm not skilled to understand deeply how the layout paragraph component form controller works to make real investigations. Though, I could take time to test things if needed.