public class WalletNotHandled {
    sealed interface Payment permits Card, Upi, NetBanking, Wallet {}     // Wallet added
    record Card(long amount) implements Payment {}
    record Upi(long amount) implements Payment {}
    record NetBanking(long amount) implements Payment {}
    record Wallet(long amount) implements Payment {}

    // Same switch as before, with no default and no case for Wallet.
    static long fee(Payment p) {
        return switch (p) {
            case Card c -> c.amount() * 2 / 100;
            case Upi u -> 0;
            case NetBanking n -> 10;
        };
    }
}