Cannot serialize class - not found: com.example.userservice.dto.UserCreatedPayload error

[huseyingoztok]

Even though my UserCreatedPayload class implements Serializable, I am receiving the error mentioned in the title. I would appreciate your guidance on the cause of this error.

I receive the error after the line outbox.schedule(getClass()).sendCreatedUser(payload); is processed.

Example codes

`package com.example.userservice.service;

import com.example.userservice.config.kafka.producer.KafkaProducer;
import com.example.userservice.config.kafka.properties.UserCreatedTopicProperties;
import com.example.userservice.dto.UserCreateRequest;
import com.example.userservice.dto.UserCreatedPayload;
import com.example.userservice.entity.User;
import com.example.userservice.repository.UserRepository;
import com.gruelbox.transactionoutbox.TransactionOutbox;
import lombok.RequiredArgsConstructor;
import org.springframework.messaging.support.GenericMessage;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.HashMap;
import java.util.Map;
import java.util.Optional;

import static org.springframework.kafka.support.KafkaHeaders.*;

@service
@requiredargsconstructor
public class UserService {

private final UserRepository userRepository;

private final KafkaProducer kafkaProducer;

private final UserCreatedTopicProperties userCreatedTopicProperties;
private final TransactionOutbox outbox;

@Transactional
public User create(UserCreateRequest userCreateRequest) {
    User user = User.getUser(userCreateRequest);
    User savedUser = userRepository.save(user);

    UserCreatedPayload payload = UserCreatedPayload.GetUserCreatedPayload(savedUser, userCreateRequest.getAddressText());
    outbox.schedule(getClass()).sendCreatedUser(payload);
    return savedUser;
}

public User getUserById(Long id) {
    Optional<User> userOptional = userRepository.findById(id);
    if (!userOptional.isPresent()) {
        return null;
    }
    return userOptional.get();
}

public void sendCreatedUser(UserCreatedPayload payload) {
    Map<String, Object> headers = new HashMap<>();
    headers.put(TOPIC, userCreatedTopicProperties.getTopicName());
    headers.put(MESSAGE_KEY, payload.getId().toString());

    kafkaProducer.sendMessage(new GenericMessage<>(payload, headers));
}

}
`