VegaDsl
case class VegaDsl(axes: Option[Seq[Axis]], data: Option[Seq[Data]], encode: Option[VegaEncode], layout: Option[Layout], legends: Option[Seq[Legend]], marks: Option[Seq[Mark]], projections: Option[Seq[Projection]], scales: Option[Seq[Scale]], signals: Option[Seq[Signal]], title: Option[Title], usermeta: Option[Map[String, Option[Json]]], $schema: Option[String], autosize: Option[Autosize], background: Option[BackgroundElement], config: Option[Map[String, Option[Json]]], description: Option[String], height: Option[HeightElement], padding: Option[Padding], style: Option[Style], width: Option[HeightElement])