SpringBoot返回对象时,如何将Long类型转换为String

public class JacksonMapper extends ObjectMapper {
  public JacksonMapper() {
    super();
    this.configure(JSONGenerator.Feature.WRITE_BIGDECIMAL_AS_PLaiN, true);
    this.configure(jsonGenerator.Feature.IGNORE_UNKNOWN, true);
    this.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    this.setSerializationInclusion(Include.NON_NULL);
    SimpleModule simpleModule = new SimpleModule();
    simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
    simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
    simpleModule.addSerializer(long.class, ToStringSerializer.instance);
    reGISterModule(simpleModule);
  }
}

@Configuration
public class WEBConfig implements WebmvcConfigurer {
  @Autowired
  private HttpMessageConverters httpMessageConverters;
  
  @Bean
  public MappingJackson2HttpMessageConverter getMappingJackson2HttpMessageConverter() {
    return new MappingJackson2HttpMessageConverter(new JacksonMapper());
  }
  @Override
  public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
    converters.addAll(httpMessageConverters.getConverters());
  }
}

@Data
public class TestVO {
  private Long id;
}

{
    "id": "123456"
}