import java.util.List;
import java.util.ArrayList;
import java.lang.Integer;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.Optional;

public class Bug309 {
    public main() {
        List<Integer> list = new ArrayList<>(List.of(1,2,3,4,5,6,7,8,9));
        var res = list.stream().filter(x -> x == 5).map(x -> x * 2).findFirst();
        return res;
    }
}
