Currently, the following schema definition fails with
SchemaException: Cannot handle enum class class com.apurebase.kgraphql.FilmType as Object type :

schema {
    query("getEnum") {
        resolver { -> FilmType.FULL_LENGTH }
    }
}

To make it work, one has to manually register the enum via DSL:

schema {
    enum<FilmType>()
    query("getEnum") {
        resolver { -> FilmType.FULL_LENGTH }
    }
}

It should be possible to get rid of that manual step and handle enums automatically.