------
 Relocating Classes
 ------
 Mauro Talevi
 ------
 2008-07-21
 ------

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Relocating Classes

  If the uber JAR is reused as a dependency of some other project, directly including classes from the artifact's
  dependencies in the uber JAR can cause class loading conflicts due to duplicate classes on the class path. To
  address this issue, one can relocate the classes which get included in the shaded artifact in order to create a
  private copy of their bytecode:

+-----
<project>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>${project.version}</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <relocations>
                <relocation>
                  <pattern>org.codehaus.plexus.util</pattern>
                  <shadedPattern>org.shaded.plexus.util</shadedPattern>
                  <excludes>
                    <exclude>org.codehaus.plexus.util.xml.Xpp3Dom</exclude>
                    <exclude>org.codehaus.plexus.util.xml.pull.*</exclude>
                  </excludes>
                </relocation>
              </relocations>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>
+-----

  This instructs the plugin to move classes from the package <<<org.codehaus.plexus.util>>> and its subpackages
  into the package <<<org.shaded.plexus.util>>> by moving the corresponding JAR file entries and rewritting the
  affected bytecode. The class <<<Xpp3Dom>>> and some others will remain in their original package.