pom.xml

<plugins>
            <plugin>
                <groupId>ro.isdc.wro4j</groupId>
                <artifactId>wro4j-maven-plugin</artifactId>
                <version>1.4.3</version>
                <executions>
                    <execution>
                        <phase>compile</phase>
                        <goals>
                            <goal>run</goal>
                        </goals>
                        <configuration>
                            <destinationFolder>${project.build.directory}/${project.build.finalName}/</destinationFolder>
                            <jsDestinationFolder>${project.build.directory}/${project.build.finalName}/resources/js</jsDestinationFolder>
                            <cssDestinationFolder>${project.build.directory}/${project.build.finalName}/resources/styles</cssDestinationFolder>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>

wro.xml

<groups xmlns="http://www.isdc.ro/wro">
    <group name="g1">
        <js>classpath:com/mysite/resource/js/1.js</js>
        <css>classpath:com/mysite/resource/css/1.css</css>
        <group-ref>g2</group-ref>
    </group>
</groups>