Why rebuild of Kotlin application removes target class files in Eclipse?

Question

I'm trying to setup an app written in Kotlin, built on Maven and using Spring Boot in Eclipse.

I manage to run the application only if I do Maven build of the project which generates class files in target/classes dir. If I do clean the project then Eclipse rebuilds it automatically and removes all class files from target/classes dir.

I think that re-build of the project should re-compile class files in target/classes directory, not just to remove them. Otherwise it means that I need to re-build project as Maven on each code change which I seems to be a wrong way to go.

Please point me the correct way to setup a Kotlin - Maven - Spring Boot project in Eclipse.

My setup is:

• Eclipse is 4.26.0.
• Maven EMBEDDED 3.8.6.
• Kotlin Plugin for Eclipse 0.8.24 (it causes intallation of Enhanced Kotlin for Eclipse plugin).
• Spring Tools 4 - 4.17.2.RELEASE.
• OpenJDK 11.0.2.

What I did:

1. Installed all the above (Eclipse, plugins, JDK and etc).
2. Imported the project as a Maven project in Eclipse: github link.

Import dialog

3. Right click on DemoApplication.kt -> Run As -> 1 Kotlin Application. I got an error:

Error: Could not find or load main class com.example.demo.DemoApplicationKt
Caused by: java.lang.ClassNotFoundException: com.example.demo.DemoApplicationKt

4. Right click on pom.xml -> Run As -> 2 Maven build...
5. Goals: clean install -> Run.
6. After that I see in {project dir}\target\classes\com\example\demo class files were generated.
7. If then I do right click on DemoApplication.kt -> Run As -> 1 Kotlin Application it runs OK.
8. If I click on Project -> Clean... (with Build Automatically ON) - all files from {project dir}\target\classes\com\example\demo got removed and I again start at point 3.

I tried couple configuration options, but they didn't help:

1. Making Window -> Preferences -> Java -> Compiler -> Building -> Output folder -> Scrub output folders when cleaning projects OFF doesn't help - class files still got removed.
2. In Package Explorer -> Kotlin Runtime Library there is a virtual directory kotlin_bin which has all class files. I tried to setup it as Dependencies:

Run Configuration dependencies setup

But it fails to run then with the below error:

Error when run it