一些Idea问题,注解意义

1.如果下载插件(Plugins)时出现"marketplace plugins are not loaded"问题，则把“use secure connection”的√去掉，再重启Idea
参考：http://www.mamicode.com/info-detail-2602604.html

2. lombok下的@Getter 和 @Setter注释如果加在class上，自动为每一个variable添加getter和setter方法；如果加在variable上，则只为那个variable加
   参考：https://springframework.guru/spring-boot-with-lombok-part-1/

3.@RequiredArgsConstructor: generates a constructor with 1 parameter for each field that requires special handling. All non-initialized final fields get a parameter, as well as any fields that are marked as @NonNull that aren’t initialized where they are declared. For those fields marked with @NonNull, an explicit null check is also generated. The constructor will throw a NullPointerException if any of the parameters intended for the fields marked with @NonNull contain null. The order of the parameters match the order in which the fields appear in your class.
参考：https://projectlombok.org/features/constructor

4. @AggregateRoot, 由此注释的class管理所有它包含的variable.