Opening IndexingNotificationProviderImpl shows error badges in file icon only

### Apache NetBeans version

Apache NetBeans 26

### What happened

Posting this since it is often difficult to get reproducers for issues like this.

build NB project

open:
```
java/maven.indexer.ui/src/org/netbeans/modules/maven/indexer/IndexingNotificationProviderImpl.java
```

check:

in log:
```
WARNING [org.netbeans.modules.java.source.tasklist.IncorrectErrorBadges]: Incorrect error badges detected, file=/home/mbien/NetBeansProjects/netbeans/java/maven.indexer.ui/src/org/netbeans/modules/maven/indexer/IndexingNotificationProviderImpl.java.
WARNING [org.netbeans.modules.java.source.tasklist.IncorrectErrorBadges]: Going to recompute root=/home/mbien/NetBeansProjects/netbeans/java/maven.indexer.ui/src, files in error=[file:/home/mbien/NetBeansProjects/netbeans/java/maven.indexer.ui/src/org/netbeans/modules/maven/indexer/IndexingNotificationProviderImpl.java].
```

reproducible in NB 26 and current master (javac 25)

### Language / Project Type / NetBeans Component

java netbeans ant project

### How to reproduce

see above

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

No / Don't know

### Operating System

linux

### JDK

24 + 25

### Apache NetBeans packaging

Apache NetBeans binary zip

### Anything else

_No response_

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

No

Build the NetBeans project and open java/maven.indexer.ui/src/org/netbeans/modules/maven/indexer/IndexingNotificationProviderImpl.java with JDK 24 or 25. Start with the logged IncorrectErrorBadges warnings and compare the displayed file icon with the reported diagnostics; done means the incorrect error badge no longer appears and the warnings are absent.

Written by the indexing model from the issue text.