isNullOrBlank

import kotlin.test.*

fun main() { 
   //sampleStart 
   fun validateName(name: String?): String {
    if (name.isNullOrBlank()) throw IllegalArgumentException("Name cannot be blank")
    // name is not nullable here anymore due to a smart cast after calling isNullOrBlank
    return name
}

println(validateName("Adam")) // Adam
// validateName(null) // will fail
// validateName("") // will fail
// validateName("  \t\n") // will fail 
   //sampleEnd
}