DESCRIBE THE ISSUE IN DETAIL:

Accessing the sources of a variant in the build.gradle.kts makes the lazy initializer initialize too early in ComponentImpl. The generateBuildConfigTask is not yet set and this causes the defaultJavaSources function in ComponentImpl to skip adding the build config to the source set. The same applies to aidl/renderscript/databinding/etc.

STEPS TO REPRODUCE:

Build the attached project with line 17 in app/build.gradle.kts commented and observe that /Users/kemp/git/gradle-recipes/Kotlin/manifestTransformerTest/app/build/generated/source/buildConfig/debug is printed to the console
Now uncomment line 17
Observe that it is /Users/kemp/git/gradle-recipes/Kotlin/manifestTransformerTest/app/build/generated/source/buildConfig/debug is no longer printed to the console (as well as others)

Studio Build: 2021.2.1 Patch 1 Version of Gradle Plugin: 7.2 Version of Gradle: 7.4.2 Version of Java: 11.0.12 OS: Mac OSX 12.4