Scala Circe DropNull

CirceDropNull.scala

    def _reduce(l: Seq[(String, Json)]): Json = l match {
      case ::(x, xs) =>
        if (x._2.isNull) {
          dropNull(Json.fromFields(xs))
        } else {
          val jj = Json.fromJsonObject(JsonObject((x._1, dropNull(x._2))))
          xs match {
            case Nil => jj
            case _   => dropNull(Json.fromFields(xs)).deepMerge(jj)
          }
        }
      case Nil => Json.Null
    }

    def dropNull(j: Json): Json = j.asObject match {
      case None =>
        j.asArray match {
          case Some(value) =>
            Json.fromValues(value.map { a =>
              a.asObject.map(_.toList match {
                case x :: xs =>
                  _reduce(x :: xs)
                case Nil => Json.Null
              })
              dropNull(a)
            })
          case None => j
        }

      case Some(value) =>
        value.toList match {
          case Nil => j
          case l   => _reduce(l)
        }
    }