UIRadioButtons with ENUM_VALUES_INCL_NULL and DISABLED always renders the NULL Option

[Jiguro]

Dear Linkki Team,

I would like to report the following behaviour with the Linkki UI element UIRadioButtons, which I have discovered with Linkki 2.3.1 (but can also be reproduced in 2.3.3):

When NULL is allowed as one of the radio options (e.g. via ENUM_VALUES_INCL_NULL annotation attribute) but the element is disabled (e.g. via DISABLED annotation attribute), then the NULL option is always rendered as the selected option, even though the underlying model value field has a value that is not NULL.

I have attached a zipped Linkki project below with which this behaviour can be reproduced (project created with Spring Boot maven archetype for Linkki 2.3.3). Here is also a screenshot, where the problem is displayed with Element "Weekday2", marked in red:

I hope you can provide guidance on how I can achieve the result that a disabled radiobutton still renders the underlying model value as the selected option instead of NULL option.

With kind regards and many thanks,
Tri

my-test-app.zip