Scala/Java integration will always be somewhat of a problem, that requires thought and effort to get right. Any default way of converting between classes will leave some people going "WTF?". Jorge Ortiz's scala-javautils[1] can be helpful. Googling for these utils will lead to some blogposts discussing the problems of fully automatic conversion.
[1] http://github.com/jorgeortiz85/scala-javautils