isBlank 
  Returns true if this char sequence is empty or consists solely of whitespace characters according to Char.isWhitespace.
Since Kotlin
1.0Samples
import kotlin.test.*
fun main() { 
   //sampleStart 
   fun validateName(name: String): String {
    if (name.isBlank()) throw IllegalArgumentException("Name cannot be blank")
    return name
}
println(validateName("Adam")) // Adam
// validateName("") // will fail
// validateName("  \t\n") // will fail 
   //sampleEnd
}