Make generated classes package-private
By default, generated classes (and methods) are public. Make them package-private by setting the publicVisibility configuration element to false.
<project>
...
<build>
<plugins>
...
<plugin>
<groupId>com.github.robtimus</groupId>
<artifactId>i18n-maven-plugin</artifactId>
<version>3.1</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<bundleName>com.foo.bar.i18n</bundleName>
<publicVisibility>false</publicVisibility>
</configuration>
</execution>
</executions>
</plugin>
...
</plugins>
</build>
...
</project>