[SCB-2752] Filter out configurations with empty values

[yanghao605]

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[liubao68]

Can you provide any information on how to reproduce the problem?

[yanghao605]

我是在ConfigurationSpringInitializer的单元测试类中传了个值为null的环境变量，他这个在将配置由spring添加到archaius的时候，没有对value做非空校验，在后续的逻辑中会导致空指针异常

[liubao68]

但是实际场景是怎么发生的了？ 环境变量按照道理不会存在 null 的情况。

[yanghao605]

有的业务将配置存储在数据库中，在服务启动的时候，从数据库中读取配置信息，并塞入spring的配置中，从而导致可能产生value为空的配置项

[liubao68]

如果是这样， 我理解这个修改不是很完整。 archaius不支持value=null的配置项， 而其他配置源支持，所以比较合理的修改应该是在将其他配置源复制到archaius的时候，统一过滤掉value=null的MAP键值对。