如何使用 Optional orElseThrow

Question

spec java 11 (openjdk11)
spring boot 2.3.6
intellij

Here is..
Show image

@Service
@RequiredArgsConstructor
public class PostService {

    private final PostRepository postRepository;
    public PostDto.Response getPostById(long postId) {
        Post post = postRepository.findById(postId)
                .orElseThrow(RuntimeException::new);    // <-- this line
        return new PostDto.Response(post);
    }
}

and alse
Show image

@Service
@RequiredArgsConstructor
public class PostService {

    private final PostRepository postRepository;
    public PostDto.Response getPostById(long postId) {
        Post post = postRepository.findById(postId)
                .orElseThrow(() -> new RuntimeException());  // <-- this line
        return new PostDto.Response(post);
    }
}

But It works..
Why is that red underline displayed?
Show Message1
Show Message2