[MNG-6764] Maven sources plugin uses configuration different than expected

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Invalid
• Labels: maven maven3,
• Environment: Maven 3.5.4
• Assignee: Unassigned
• Reporter: Adrian Wyssmann
• Created: 12/Sep/19 11:54
• Updated: 12/Sep/19 16:06
• Resolved: 12/Sep/19 16:06

Description

While debugging the problem described here, I've noticed something strange.

I have a project which has the following config for the "maven-source-plugin"

...
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-source-plugin</artifactId>
                <configuration>
                    <attach>true</attach>
                </configuration>
            </plugin>

and the this in the parent-pom

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-source-plugin</artifactId>
                    <version>3.1.0</version>
                    <executions>
                        <execution>
                            <id>attach-sources</id>
                            <goals>
                                <goal>jar</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin> 

As the sources-jar is uploaded twice the build fails, thus I checked the "effective pom" by running

mvn -Prelease-profile help:effective-pom

The result is strange as the configuration for the maven-source-plugin is something totally different. Once under "pluginManagement"

    <build>
        ...
        <pluginManagement>
           ...
           <plugin>
            <artifactId>maven-source-plugin</artifactId>
            <version>2.2.1</version>
            <executions>
              <execution>
                <id>attach-sources</id>
                <goals>
                  <goal>jar</goal>
                </goals>
              </execution>
            </executions>
            ...
        </pluginManagement>

and once under "plugins"

    <build>
        ...
        </pluginManagement>
        <plugins>
          <plugin>
            <artifactId>maven-source-plugin</artifactId>
            <version>2.2.1</version>
            <executions>
                <execution>
                <id>attach-sources</id>
                <goals>
                    <goal>jar-no-fork</goal>
                    <goal>jar</goal>
                </goals>
                <configuration>
                    <attach>true</attach>
                </configuration>
                </execution>
            </executions> 

I don't understand how this is possible and where the config comes from. Is this a bug? Something I miss?