FunctionProcessor.kt

override fun visitTypeArgument(typeArgument: KSTypeArgument, data: Unit) {
    when (val variance: Variance = typeArgument.variance) {
        STAR -> {
            file += "*"
            return
        }
        COVARIANT, CONTRAVARIANT -> {
            file += variance.label // 'out' or 'in'
            file += " "
        }
        INVARIANT -> {
            // do nothing
        }
    }
}