Update Maven Assembly plugin from unspecified to 3.0.0 to fix building
on Java 9. The build goes further than failing right away but still
fails. Note that you also need to set maven_opts=--add-modules
ALL-SYSTEM
</execution>
</executions>
</plugin>
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-assembly-plugin</artifactId>
+ <version>3.0.0</version>
+ </plugin>
</plugins>
</pluginManagement>
<plugins>
