class Person(val name: String) {
    constructor(vararg longName: String) /* : this(sj.toString()) */ {
        val sj = java.util.StringJoiner(" ")
        longName.forEach { sj.add(it) }
    }
}

class Person(vararg longName: String) {

    val name = longName.joinToString(" ")
}

class Person(vararg longName: String) {

    val name: String

    init {
        name = longName.joinToString(" ")
    }
}