<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
    </plugin>
  </plugins>
</build>

<project>
  [...]
  <build>
    [...]
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <executions>
          <execution>
            <id>make-uber-jar</id> <!-- this is used for inheritance merges -->
            <phase>packaging</phase> <!-- append to the packaging phase. -->
            <goals>
              <goal>single</goal> <!-- goals == mojos -->
            </goals>
            <configuration>
              <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
              </descriptorRefs>
            </configuration>
          </execution>
          <execution>
            <id>make-distribution</id> <!-- this is used for inheritance merges -->
            <phase>packaging</phase> <!-- append to the packaging phase. -->
            <goals>
              <goal>single</goal> <!-- goals == mojos -->
            </goals>
            <configuration>
              <descriptors>
                <descriptor>src/assembly/distribution.xml</descriptor>
              </descriptors>
            </configuration>
          </execution>
        </executions>
      </plugin>
      [...]
</project>