Fix for GRAILS-11647 It's not possible to override collection properties with custom Hibernate User types (master branch) 

This is a follow up for GRAILS-10335 which I fix a year ago. It turns out that even with that patch it's not possible to handle the mapping of a Collection with a custom hibernate user type. The problem is that the collection property is marked as not persistant, so when the execution flows reach the code in that patch, as the property is not persistent, it's ignored.

Reading the comments around the code (in the patch), the Set properties are handled and also Collections but these are only handle in one place but not in the other one. With this patch, collections are also handled.
I've created a test and a patch and I'm going to submit the patch agains master, 2.4.x and 2.3.x branches.