How to create an additional attached jar artifact from the project

Specify a list of fileset patterns to be included or excluded by adding <includes>/<include> or <excludes>/<exclude> and add a classifier in your pom.xml.

Note: the jar-plugin must be defined in a new execution, otherwise it will replace the default use of the jar-plugin instead of adding a second artifact. The classifier is also required to create more than one artifact.

<project>
  ...
  <build>
    <plugins>
      ...
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>3.0.0</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>jar</goal>
            </goals>
            <configuration>
              <classifier>client</classifier>
              <includes>
                <include>**/service/*</include>
              </includes>
            </configuration>
          </execution>
        </executions>
      </plugin>
      ...
    </plugins>
  </build>
  ...
</project>