finalName is created as:
<build>
<finalName>${project.artifactId}-${project.version}</finalName>
</build>
One of the solutions is to add own property:
<properties>
<finalName>${project.artifactId}-${project.version}</finalName>
</properties>
<build>
<finalName>${finalName}</finalName>
</build>
And now try:
mvn -DfinalName=build clean package