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From: "Wangda Tan (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HADOOP-11199) Configuration should be able to
 set empty value for property
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    [ https://issues.apache.org/jira/browse/HADOOP-11199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14179682#comment-14179682 ] 

Wangda Tan commented on HADOOP-11199:
-------------------------------------

[~rchiang], thanks for you patch,
Actually, I don't think this is intentional, because we cannot set an empty value instead of null for a key in configuration. And the empty value configuration should be a determinate behavior instead of a configurable one, there's complete different semantics between empty and null. I think if a existing module rely on behavior today should be updated. Do you have any example for configs rely on this? 

Thanks,
Wangda

> Configuration should be able to set empty value for property
> ------------------------------------------------------------
>
>                 Key: HADOOP-11199
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11199
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: conf
>            Reporter: Wangda Tan
>         Attachments: HADOOP-11199-01.patch
>
>
> Currently in hadoop.common.conf.Configuration, when you specify a XML like this:
> {code}
> <configuration>
>   <property>
>     <name>conf.name</name>
>     <value></value>
>   </property>
> </configuration>
> {code}
> When you trying to get the conf.name, the returned value is null instead of an empty string.
> Test code for this,
> {code}
> import java.io.ByteArrayInputStream;
> import org.apache.hadoop.conf.Configuration;
> public class HadoopConfigurationEmptyTest {
>   public static void main(String[] args) {
>     Configuration conf = new Configuration(false);
>     ByteArrayInputStream bais =
>         new ByteArrayInputStream(("<configuration><property>"
>             + "<name>conf.name</name>" + "<value></value>"
>             + "</property></configuration>").getBytes());
>     conf.addResource(bais);
>     System.out.println(conf.get("conf.name"));
>   }
> }
> {code}
> Does this intentionally or a behavior should be fixed?



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