Will be very useful to document that API support partial responses.
This will give a strong point when comparing with GraphQL.

Like GET /api/blogposts?fields=author{name,avatar},title,detail

https://www.leliam.com/make-rest-api-to-partial-response-just-like-graphql-@bRyL6nWufIxFXIdNWRdAwN
https://apigee.com/about/blog/technology/restful-api-design-can-your-api-give-developers-just-information-they-need

To achieve this we need a way to check if a string like "author{name,avatar},title,detail" is a valid path in some class. Something like

class User {
    String name;
    String avatar;
    int age;
    // ...
}
class Post {
    User author;
    String title;
    String detail;
    int rating;
    // ...
}

class Request {
    String data;
    @JsonPath(Post.class)
    String fields;
    // ...
}

So, @JsonPath(Post.class) will check if string value is a valid path in Post class.