GraphQL Client with spring boot

I have a spring boot GraphQL API and I want to consume it in another spring boot app using GraphQL Client. I am using spring boot version 3.
when I execute mutate which works as data is added to the database, I am not able to figure out how to convert the received response to java class. below is my ClientService class.
any advise?
note: it only worked for me is by using Map to get key value pairs of the received object.
ObjectMapper didnt work.

package com.webtech.graphqlclient.service;

import com.webtech.graphqlclient.webmodels.CreateStudentRequest;
import com.webtech.graphqlclient.webmodels.StudentResponse;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.graphql.client.HttpGraphQlClient;
import org.springframework.stereotype.Service;
import org.springframework.web.reactive.function.client.WebClient;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

@Service
public class ClientService {

private final HttpGraphQlClient graphQlClient;

public ClientService(@Value("${graphql.api.url}")String apiUrl) {
    WebClient client = WebClient.builder()
            .baseUrl(apiUrl)
            .build();

    graphQlClient  = HttpGraphQlClient.builder(client).build();
}

public StudentResponse getStudent(int id){

    Map<String, Object> variables = new HashMap<>();

    variables.put("id", id);

    String query = """
            query getStudent($id: Int) {
              getStudent(id: $id) {
                id
                firstName
                lastName
                email
                street
                city
                fullName
                subjects(subjectNameFilter: All) {
                  id
                  subjectName
                  marksObtained
                }
              }
            }
            """;

    return graphQlClient.document(query)
            .variables(variables)
            .retrieve("getStudent")
            .toEntity(StudentResponse.class)
            .block();
}

public StudentResponse createStudent(CreateStudentRequest createStudentRequest) {

    Map<String, Object> variables = new HashMap<>();
    variables.put("createStudentRequest", createStudentRequest);

    String mutationQuery = """
            mutation createStudent($createStudentRequest: CreateStudentRequest) {
              createStudent(createStudentRequest: $createStudentRequest) {
                id
                firstName
                lastName
                email
                street
                city
                fullName
                subjects(subjectNameFilter: All) {
                  id
                  subjectName
                  marksObtained
                }
              }
            }
            """;

     Map<String, Object> data = 
Objects.requireNonNull(graphQlClient.document(mutationQuery)
                     .variables(variables)
                     .execute()
                     .block())
            .getData();

    Map<String, Object> entity = (Map<String, Object>) data.get("createStudent");

    int id = (int) entity.get("id");

    return getStudent(id);

}
}