Kotlin compiler reports unused expression in constructor for builder taking vararg lambdas We have a relatively simple builder pattern we use for test data generator in Kotlin. The builders follow the pattern: class ThingBuilder private constructor( var param1: Int = 1, var param2: Boolean = true ) { private constructor(vararg inits: ThingBuilder.(ThingBuilder) -> Unit) : this() { inits.forEach { it(this) } } fun build(): Thing { return Thing( param1, param2 ) } companion object { fun...