zhaijack commented on issue #414: Test failure in UpdateLedgerOpTest URL: https://github.com/apache/bookkeeper/issues/414#issuecomment-321207830 discussed this issue with @sijie on slack channel, and work together to figure out the reason. Thanks @sijie for the help. Here is how [CompositeConfiguration](https://commons.apache.org/proper/commons-configuration/apidocs/org/apache/commons/configuration2/CompositeConfiguration.html) works: ``` CompositeConfiguration allows you to add multiple Configuration objects to an aggregated configuration. If you add Configuration1, and then Configuration2, any properties shared will mean that the value defined by Configuration1 will be returned. If Configuration1 doesn't have the property, then Configuration2 will be checked. You can add multiple different types or the same type of properties file. When querying properties the order in which child configurations have been added is relevant. To deal with property updates, a so-called in-memory configuration is used. Per default, such a configuration is created automatically. All property writes target this special configuration. There are constructors which allow you to provide a specific in-memory configuration. If used that way, the in-memory configuration is always the last one in the list of child configurations. This means that for query operations all other configurations take precedence. ``` To achieve this goal, setProperty will first [clearProperty](https://github.com/apache/commons-configuration/blob/trunk/src/main/java/org/apache/commons/configuration2/CompositeConfiguration.java#L361) and then do addProperty. While in our use case: ServerConfiguration conf = new ServerConfiguration(baseConf); conf.setAllowLoopback(true); < == this will clear the value in baseConf first, and cause we get un-wanted value. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
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