private String myName;
private NestedBean nestedBean;

@AllArgsConstructor
@Data
public static class NestedBean {

    private String myId;
}

public static void main(String[] args) {
    DemoBean demoBean = new DemoBean();
    demoBean.setMyName("test name");
    demoBean.setNestedBean(new NestedBean("test id"));
    SerializeConfig serializeConfig = new SerializeConfig();
    serializeConfig.propertyNamingStrategy = PropertyNamingStrategy.SnakeCase;

    System.out.println(JSON.toJSON(demoBean, serializeConfig));

}