Here is what you want:
```scala
import scala.collection.mutable.{Map => MMap}
import scala.collections.JavaConverters._

// At the end of the def config method:
val tempMap = MMap[AnyRef, String](config.toSeq :_*)
AppProps.addApplicationFramework(tempMap.asJava,
  String.format("scalding:%s", config.get("scalding.version").get))
return tempMap.toMap // view it as an immutable map
```