safeargs-alt.scala

type Arguments = Args[A] forSome { type A }

final class Args[A: SafeArgument](val underlying: Map[String, A])

object Arguments {
  def empty: ArgumentsAlt[String] = new ArgumentsAlt(Map.empty)
  def apply[V: SafeArgument](kv: (String, V)*): ArgumentsAlt[V] = 
    new ArgumentsAlt(kv.toMap)
}

implicit def argumentConversion[A](arguments: ArgumentsAlt[A])(implicit ev: Evidence[SafeArgument]): java.util.Map[String, Object] =
  arguments.underlying.map { case (k, v) => k -> SafeArgument[A].toObject(v) }.asJava