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>