Document Groups don't import correctly

### Apache NetBeans version

Apache NetBeans 19

### What happened

When importing the settings, all document groups are transferred correctly, but the documents themselves are not. I have been registering the problem since version 17.

### How to reproduce

_No response_

### Did this work correctly in an earlier version?

Apache NetBeans 17

### Operating System

linux

### JDK

openjdk version "11.0.20.1" 2023-08-24 OpenJDK Runtime Environment (build 11.0.20.1+1-post-Ubuntu-0ubuntu122.04) OpenJDK 64-Bit Server VM (build 11.0.20.1+1-post-Ubuntu-0ubuntu122.04, mixed mode, sharing)

### Apache NetBeans packaging

Apache NetBeans provided installer

### Anything else

_No response_

### Are you willing to submit a pull request?

No

Start by reproducing settings import on Apache NetBeans 19 under Linux with OpenJDK 11, focusing on document groups and their documents. Trace the settings-import entry point and compare the imported group contents with the source; done when both groups and their documents transfer correctly.

Written by the indexing model from the issue text.