import org.springframework.integration.support.MessageBuilder;
import org.springframework.messaging.MessageChannel;

@Component
class UserEventGateway {

    @JsonIgnore
    private final MessageChannel messageChannel;

    private final UserInfoRepository userInfoRepository;
(...)
  @EventListener
    public void handleUserInfoUnregisteredEvent(UserInfoUnregisteredEvent userInfoUnregisteredEvent) {
        UserEventDto userUnRegisteredEventDto = UserEventAssembler.toUserUnregisteredEvent(userInfoUnregisteredEvent);
// send event this is where the exception starts ---------------------------------------˘
        this.messageChannel.send(MessageBuilder.withPayload(userUnRegisteredEventDto).build());
    }
}