Insert a dependent jar into an installer jar

<plugin>
  <artifactId>maven-assembly-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
        <mainClass>com.example.installer.Installer</mainClass>
      </manifest>
    </archive>
  </configuration>
</plugin>

<assembly>
  <id>installer</id>

  <formats>
    <format>jar</format>
  </formats>

  <baseDirectory></baseDirectory>

  <dependencySets>
    <dependencySet>
      <outputDirectory>/</outputDirectory>
      <includes>
        <!-- this references your installer sub-project -->
        <include>com.example:installer</include>
      </includes>
      <!-- must be unpacked inside the installer jar so it can be executed -->
      <unpack>true</unpack>
      <scope>runtime</scope>
    </dependencySet>
    <dependencySet>
      <outputDirectory>/</outputDirectory>
      <includes>
        <!-- this references your server.war and any other dependencies -->
        <include>com.example:server</include>
      </includes>
      <unpack>false</unpack>
      <scope>runtime</scope>
    </dependencySet>
  </dependencySets>
</assembly>