Why does local variable in Java have to be final in lambda (or anonymous class), but in Kotlin it doesn't have to? [duplicate]

Java: In this method, compiler gives error "Variable used in lambda expression should be final or effectively final":

void javaAnonymousClass(Button button) {
    String localVar = "10";
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            localVar = "5";
        }
    });
}

Java: In this method in "Variable 'localVar' is accessed from within inner class, needs to be final or effectively final"

void javaLambda(Button button) {
    String localVar = "10";
    button.setOnClickListener(v -> System.out.println(localVar));
    localVar = "";
}

Kotlin. No error whatsoever.

fun kotlinLambda(button: Button) {
    var localVar: String = ""
    button.setOnClickListener {
        localVar = "5"
    }
    localVar = "7"
}

My question is: WHY there is no such problem of not being final (val) in Kotlin?