Add the following fragment to your pom file to execute the SWIG plugin as part of the "generate-sources" phase.
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.freehep</groupId>
<artifactId>freehep-swig-plugin</artifactId>
<version>1.3.31-1</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<cpp>true</cpp>
<packageName>com.companyname.jni</packageName>
<source>YourCode.swg</source>
<noWarn>401 470 813 822</noWarn>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
...
</project>