Kotlin classes not seen across Gradle subprojects

### Apache NetBeans version

Apache NetBeans 28 latest daily build

### What happened

Once I open Gradle multi-module project contains both Java and Kotlin classes I see error badges in editor over Kotlin classes imported to one sub-project from other.

### Language / Project Type / NetBeans Component

Gradle multi-module project with Java/Kotlin sources

### How to reproduce

Open attached demo project

[MixedLangProject.zip](https://github.com/user-attachments/files/22425451/MixedLangProject.zip)

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

No / Don't know

### Operating System

Ubuntu Linux / Windows

### JDK

Java: 17.0.10; OpenJDK 64-Bit Server VM 17.0.10+13-LTS

### Apache NetBeans packaging

Own source build

### Anything else

_No response_

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

No

Start by opening the attached MixedLangProject.zip in an Apache NetBeans 28 daily build on a multi-module Gradle project containing Java and Kotlin sources. Reproduce the editor error badges on Kotlin classes imported between subprojects, then verify that those badges no longer appear while cross-project Kotlin references resolve correctly.

Written by the indexing model from the issue text.