neat-validation/neat/required

required

fun <T> Validators<T>.required(message: String = " is required, but was null"): Validator<T>
fun <P, C : Any> PropertyValidators<P, C>.required(message: String = " is required, but was null"): Validator<C>
val <T : Any> KProperty0<T?>.required: T
val Validator<*>.required: Boolean