Serious, hard to trace bug in core DirtyCheckingSupport class

[lkuchars]

Grails 4.0.3
grails-datastore-core:7.0.6-RELEASE
grails-datastore-gorm-mongodb:7.0.1

I Am sorry I will not be able to provide you with unit test for this. This error is too intricate. I'm chasing this problem for days on 2 production systems where mongo mapped Domain entities are not updated in database because dirty properties are not detected properly.

Let me explain why this happens and hopefully you can follow me with the reasoning as this, I believe is sth that is almost impossible to debug.

It all boils down to this fragment and how the marker in question is initialized.

Because ^^^^^ it is mutable and assigned around to other references in the code the marker can and eventually is modified. In specific circumstances it comes to the point where my system in question lands in following state:

And event which make my system goes into this state is pretty common:

It turns out that in my case when OptimisticLockingException is thrown ^^^^^^ it causes DirtyCheckingSupport.DIRTY_CLASS_MARKER left non empty. Well i guess it should not be modifiable in the first place. Let me mention that I DO NOT modify or use those references anywhere in my code.
I guess that it is inevitable that when mutable collection is used as marker, for example in DirtyCheckable.groovy like this:

enetually $changedProperties will be modified by someone and marker will be modified too.

My suggestion is to initialized this marker like this:
Map DIRTY_CLASS_MARKER = [:].asImmutable()

Then at least we will know where and when another library tries to modify it and we will fail fast

Thanks