Android app throws NoClassDefFoundError after setting Gradle SourceSets

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1

Hi,

I am trying to understand how to set sourcesets in build.gradle.kts file. For that i have a test project. The project structure is as follows-
app
-src
–main
—java
----com.example.myapplication
-----MainActivity.kt
–sample2
—java
----com.example.myapp.legacy
-----LegacyFile.java

LegacyFile.java

package com.example.myapp.legacy;

public class LegacyFile {

}

Here, i wan to create instance of LegacyFile inside MainActivity.kt file -

    override fun onCreate(savedInstanceState: Bundle?) {
....
        val legacyFile = LegacyFile()
}

So, i added the following lines to app/build.gradle.kts file -

android {
.....
    sourceSets.getByName("main").apply {
        kotlin.setSrcDirs(listOf("src/sample2/java"))
    } 
}

Now, the project compiles successfully. But, when i run the app it throws an exception -
FATAL EXCEPTION: main Process: com.example.myapplication, PID: 2436 java.lang.NoClassDefFoundError: Failed resolution of: Lcom/example/myapp/legacy/LegacyFile; at com.example.myapplication.MainActivity.onCreate(MainActivity.kt:25) … Caused by: java.lang.ClassNotFoundException: Didn’t find class “com.example.myapp.legacy.LegacyFile” on path: DexPathList[[dex file “/data/data/com.example.myapplication/code_cache/.overlay/base.apk/classes5.dex”, zip file “/data/app/~~5E7UPyWAZdlsGbzLHVOIJw==/com.example.myapplication-kmtHz5UXr_gzaXYqPtpKyA==/base.apk”],nativeLibraryDirectories=[/data/app/~~5E7UPyWAZdlsGbzLHVOIJw==/com.example.myapplication-kmtHz5UXr_gzaXYqPtpKyA==/lib/x86_64, /system/lib64, /system_ext/lib64]]

But, when i inspect the apk file, i can see LegacyFile.
Android Studio apk viewer

Can someone please explain what i am doing wrong here?

Thanks!

2

Update:

The exception is resolved when i set the path to java.srcDir like this-

    sourceSets.getByName("main").apply {
        java.srcDir("src/sample2/java")
    }

But, not when i set to kotlin.srcDir?? Any ideas why it behaves this way?