One alternative to this approach is to add this plugin:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<executions>
<execution>
<id>add-source</id>
<phase>generate-sources</phase>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>${project.build.directory}/generated-sources/</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>
This will allow the generated-sources to be added as a source folder so every time it generates you will have them built and available. You wouldn't commit these but when the actual jar gets built/released they will be in there and work all the same. This allows you to always be using code most up to date with your schema. This may not be the best solution for you but I found it to be a good idea when I ran into a similar situation.