The question was about creating an Option[String] from a Seq[String]

SeqStringToOptionString

object Main extends App {

  def toOpt(s: Set[String]): Option[String] = s match {
      case x if !x.isEmpty => Some(x.mkString(" "))
      case _ => None
    }
  val a: Set[String] = Set()
  val b: Set[String] = Set("a", "b")
  println(s"a = ${toOpt(a)}")
  println(s"b = ${toOpt(b)}")
}