Use Scala futures for async requests in okhttp

AsyncOkhttpScalaFutures.scala

val client : OkHttpClient = new OkHttpClient.Builder().build()
val TEXT : MediaType = MediaType.get( "text/plain; charset=utf-8" )

def asyncRequest( text : String ) : Future[ String ] = {
  val body = RequestBody.create( text, TEXT )
  val request = new Request.Builder().url( "http://michael.com" ).post( body ).build()
  
  val promise : Promise[ String ] = Promise[ String ]()
  client.newCall( httpRequest ).enqueue( new Callback {
            override def onFailure( call : Call, e : IOException ) : Unit = promise.failure( e )

            override def onResponse( call : Call, httpResponse : Response ) : Unit = promise.complete( Success( "yay!!!" ) )
   } )
  promse.future
}