Maven assembly include problem

Question

Context

We have this application, using about 60 coding projects.

We have several products that are realized using this same code base, so we follow the maven best-practices : we assemble each product using an assembly project, using the assembly plugin.

We have an historical assembly using Ant, that need many improvements. In a first phase, I am trying to obtain the same result using a clean Maven assembly. Later on, I will improve that one.

Question

In my assembly, I want to have the same jar artifact in several versions. I want:

    commons-beanutils-1.7.0.jar
    commons-beanutils-1.8.0.jar

I list both in my assembly project dependencies in my pom, but only one shows (the 1.8.0). How could I do it?

This is my pom.xml for the assembly project. Everything works if I specify only one or the other, except I don't get the other one obviously.

pom.xml:

      <dependency>
        <groupId>commons-beanutils</groupId>
        <artifactId>commons-beanutils</artifactId>
        <version>1.7.0</version>
      </dependency>
      <dependency>
        <groupId>commons-beanutils</groupId>
        <artifactId>commons-beanutils</artifactId>
        <version>1.8.0</version>
      </dependency>

Answer 1

Maven doesn't want you to do this because the behaviour at runtime is indeterminate. If you define multiple dependencies with the same groupId and artifactId, and different versions, Maven will resolve the conflict and give you one of them. You should really look at resolving the conflict so that only one version is required.

If you do have a good reason to do this, to avoid the problem you need to specify the dependencies as artifactItems in the dependency plugin. The following config will copy both versions of the jar to target/output, if the dependency plugin is executed before the assembly plugin, you will be able to include the downloaded jars in your assembly by specifying a fileSet pointing to the target/output directory:

  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <executions>
      <execution>
        <id>copy</id>
        <phase>package</phase>
        <goals>
          <goal>copy</goal>
        </goals>
        <configuration>
          <artifactItems>
            <artifactItem>
              <groupId>commons-beanutils</groupId>
              <artifactId>commons-beanutils</artifactId>
              <version>1.7.0</version>
              <type>jar</type>
              <overWrite>false</overWrite>
            </artifactItem>
            <artifactItem>
              <groupId>commons-beanutils</groupId>
              <artifactId>commons-beanutils</artifactId>
              <version>1.8.0</version>
              <type>jar</type>
              <overWrite>false</overWrite>
            </artifactItem>
          </artifactItems>
          <outputDirectory>${project.build.directory}/output</outputDirectory>
          <overWriteReleases>false</overWriteReleases>
          <overWriteSnapshots>true</overWriteSnapshots>
        </configuration>
      </execution>
    </executions>
  </plugin>