abstract class Param(val name : String) {
    val value : Option[String]
    ....
  }

  class Scope(userInfoEmail : Boolean = true,
              userInfoProfile : Boolean = true)
    extends Param("scope") {
    val value : Option[String] = {
      ...
    }
  }

 class State(value: Option[String] = None) extends Param("state")