I have a mixed kotlin/java multi-module project that uses src/main/java for the java code and src/main/kotlin for kotlin code.
For the java-only projects, everything is fine. sourceDirectory points to src/main/java, testSourceDirectory points to src/test/java. We activate a specific profile that turns on the kotlin compiler if src/main/kotlin is present. For modules that have both kotlin and java code, this works fine as well. We add src/main/kotlin to the source roots and src/test/kotlin to the test roots (using the build-helper plugin). However, for kotlin-only projects (where no src/main/java and src/test/java exists), we get a build warning: "Source root doesn't exist: .../src/main/java" (e.g. from the kotlin compiler). As we activate the compiler from a profile, we can not set the initial sourceDirectory or testSourceDirectory (overriding those values is not supported in a profile). Is there a way to clear the list of source roots in the maven project? I looked into the code and what the build helper does and tried using project.getCompileSourceRoots().clear() which works only partially. Is there an official way to clear / set the list of compileSourceRoots and testSourceRoots from a plugin that can be used from a profile? -h
