I think it is time to support Kotlin configurator.
I know Joran(XML), Gaffer(Groovy) are good enough to configure Logback. Gaffer, especially, makes the configuration compact and IDE-friendly.
I wish Logback support Kotlin configurator. Kotlin DSL is much powerful. The typed language with null-safety has got many fans lately. These are why Gradle provides Kotlin DSL API.
If you are not skeptical, I am going to open a pull-request. Please reply to any idea.