Spring boot jackson - deserializes Json with root name

I have the below Json

{
    "user": {
        "name": "Ram",
        "age": 27
    }
}

which I want to de-serialize into an instance of the class

public class User {
    private String name;
    private int age;

    // getters & setters
}

For this, I have used @JsonRootName on class name and something like below

@Configuration
public class JacksonConfig {

    @Bean
    public Jackson2ObjectMapperBuilder jacksonBuilder() {
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        builder.featuresToEnable(DeserializationFeature.UNWRAP_ROOT_VALUE);
        retu builder;
    }
}

But it did not work as expected. If I send something like below, it worked.

{
 "name": "Ram",
 "age": 27
}

But I want to get the json de-serialized with root name. Can any one please suggest?