translate-war goal produces a ClassCastException

When running translate-war goal, attached to the build lifecycle, it produces a ClassCastException.
Attached there is a log about the exception.
This is my configuration:

<profile>
<id>j4</id>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>retrotranslator-maven-plugin</artifactId>
<version>1.0-alpha-4</version>
<executions>
<execution>
<id>retrotranslate</id>
<goals>
<goal>translate-war</goal>
</goals>
<configuration>
<jarfileset>
<includes>
<include>tiles-*.jar</include>
</includes>
</jarfileset>
<classifier>j4</classifier>
<attach>true</attach>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>

You can see it live here (replacing the version of the plugin with 1.0-alpha-4):
http://svn.apache.org/repos/asf/tiles/framework/trunk/tiles-test/