Maven-assembly-plugin: custom jar filenames

I use the assembly plugin to create several jars with some classes in it. I need custom names for the resulting jars: app_business.jar app_gui.jar core.jar etc.

Currently I have to following configuration:

    <plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <configuration>
        <appendAssemblyId>false</appendAssemblyId>
    <finalName>app_business</finalName>
        <descriptors>
            <descriptor>assembly.xml</descriptor>
        </descriptors>
        <attach>true</attach>
    </configuration>
    <executions>
        <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
        </execution>
    </executions>
</plugin>

an the assembly.xml file:

    <assembly>
      <id>app_business</id>
      <formats>
        <format>jar</format>
      </formats>
      <baseDirectory>target</baseDirectory>
      <includeBaseDirectory>false</includeBaseDirectory>

      <fileSets>
        <fileSet>
          <directory>${project.build.outputDirectory}</directory>
          <outputDirectory></outputDirectory> 
          <includes>
            <include>org/xyz/**</include>
          </includes>
        </fileSet>    
      </fileSets>
    </assembly>

this creates a file app_business.jar which is perfect. But i have no idea how to create my other files. The option appendAssemblyId doesn't help me, as it creates filenames in the format AppName-app_business.jar. I really need the exact filesname app_business.jar.