Phantom Types in Kotlin: Modelling a Pipeline Request with static accessor

Request.kt

class Request<T>(
    private val image: Image?,
    private val timestamp: Timestamp?,
    private val measureSettings: MeasureSettings?,
    private val preparedImage: Mat?,
    private val scaledPreparedImage: Mat?,
    private val shapes: List<Shape>?,
    private val features: List<Feature>?,
    private val people: List<Person>?) {

    companion object {
        fun imageOf(request: Request<out ReadRawImage>): Image =
            request.image ?: throw StageException()

        fun timestampOf(request: Request<out ReadTimestamp>): Timestamp =
            request.timestamp ?: throw StageException()

        fun measureSettingsOf(request: Request<out ReadMeasureSettings>): MeasureSettings =
            request.measureSettings ?: throw StageException()

        fun preparedImageOf(request: Request<out ReadPreparedImage>): Mat =
            request.preparedImage ?: throw StageException()

        fun scaledPreparedImageOf(request: Request<out ReadPreparedImage>) =
            request.scaledPreparedImage ?: throw StageException()

        fun shapesOf(request: Request<out ReadShapes>) =
            request.shapes ?: throw StageException()

        fun featuresOf(request: Request<out ReadFeatures>) =
            request.features ?: throw StageException()

        fun peopleOf(request: Request<out ReadPeople>) =
            request.people ?: throw StageException()
    }
}