Can not set the final jar name with maven-assembly-plugin

This is how I configured maven-assembly-plugin

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.4</version>
    <configuration>
        <finalName>myapp</finalName>
        <archive>
            <manifest>
                <mainClass>com.myapp.Main</mainClass>
            </manifest>
        </archive>
        <!--
        <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
        -->
    </configuration>
</plugin>

and I expect the final jar file should be myapp.jar but it ends up with myapp-jar-with-dependencies.jar

Can you tell me how to configure to exclude "jar-with-dependencies" out of the final name?