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https://issues.apache.org/jira/browse/MNG-7596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17652610#comment-17652610
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ASF GitHub Bot commented on MNG-7596:
-------------------------------------
guylabs commented on code in PR #866:
URL: https://github.com/apache/maven/pull/866#discussion_r1058637665
##########
maven-xml-impl/src/main/java/org/apache/maven/internal/xml/Xpp3Dom.java:
##########
@@ -180,8 +181,6 @@ public void writeToSerializer(String namespace,
XmlSerializer serializer) throws
* </ol></li>
* <li> If mergeSelf == true
* <ol type="A">
- * <li> if the dominant root node's value is empty, set it to the
recessive root node's value</li>
- * <li> For each attribute in the recessive root node which is not set
in the dominant root node, set it.</li>
Review Comment:
@gnodet Why has this behavior been removed? Is there a migration path that
you can share?
The following example has worked before that change where we have a parent
pom and a child pom and a configuration that we'd like to merge. Here the
parent and child pom definitions:
```xml
<!--parent pom-->
...
<pluginManagement>
<plugins>
<plugin>
<groupId>foo.bar</groupId>
<artifactId>foo-bar-plugin</artifactId>
<configuration>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<bar>
<value>foo</value>
</bar>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<foo>
<properties>
<property>
<name>prop1</name>
<value>value1</value>
</property>
</properties>
</foo>
</plugin>
</plugins>
</configuration>
</plugin>
</plugins>
</pluginManagement>
...
<!--child pom-->
...
<pluginManagement>
<plugins>
<plugin>
<groupId>foo.bar</groupId>
<artifactId>foo-bar-plugin</artifactId>
<configuration>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<foo>
<properties combine.children="append">
<property>
<name>prop2</name>
<value>value2</value>
</property>
</properties>
</foo>
</plugin>
</plugins>
</configuration>
</plugin>
</plugins>
</pluginManagement>
...
```
And the expected effective child pom that is used after the merge:
```xml
<!--expected effective child pom-->
...
<pluginManagement>
<plugins>
<plugin>
<groupId>foo.bar</groupId>
<artifactId>foo-bar-plugin</artifactId>
<configuration>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<bar>
<value>foo</value>
</bar>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<foo>
<properties combine.children="append">
<property>
<name>prop1</name>
<value>value1</value>
</property>
<property>
<name>prop2</name>
<value>value2</value>
</property>
</properties>
</foo>
</plugin>
</plugins>
</configuration>
</plugin>
</plugins>
</pluginManagement>
...
```
The problem we see now after this change, is that it will be merged the
following way:
```xml
<!--expected effective child pom after this change-->
...
<pluginManagement>
<plugins>
<plugin>
<groupId>foo.bar</groupId>
<artifactId>foo-bar-plugin</artifactId>
<configuration>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<foo>
<properties>
<property>
<name>prop1</name>
<value>value1</value>
</property>
</properties>
</foo>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<foo>
<properties combine.children="append">
<property>
<name>prop2</name>
<value>value2</value>
</property>
</properties>
</foo>
</plugin>
</plugins>
</configuration>
</plugin>
</plugins>
</pluginManagement>
...
```
The problems are the following:
1. On the `maven-compiler-plugin` configuration the `<bar>` node is not
merged from the parent pom configuration but rather the one from the
`maven-surefire-plugin` configuration from the parent pom.
2. The `maven-surefire-plugin` configuration not as expected as the children
of the `<properties>` node are not appended as configured via the
`combine.children="append"` property.
Is that changed something that stays for Maven 4 ? I assume that then a
migration path should be given as there are projects that use the behavior
before this change and it would result in different effective pom files, which
will change how the build is configured.
I'm also open to chat about it on the ASF Slack if required or if you have
further questions.
> Upgrade to plexus-utils 3.5.0
> -----------------------------
>
> Key: MNG-7596
> URL: https://issues.apache.org/jira/browse/MNG-7596
> Project: Maven
> Issue Type: Dependency upgrade
> Reporter: Guillaume Nodet
> Assignee: Guillaume Nodet
> Priority: Major
> Fix For: 4.0.0-alpha-3, 4.0.0
>
>
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