`licenseHeader` doesn't work when `kotlin` and `kotlinGradle` are both enabled

If I use the config below, it works in Groovy Dsl project for kt fies
```groovy
spotless {
kotlin {
ktlint()
licenseHeaderFile(rootProject.file("gradle/HEADER.txt"))
}
}
```

But if I just copy-paste it into Kotlin Dsl project, license headers will not be added or replaced into kt files.