Exception overlaying zip in war

[Paul Benedict]

I configured the WAR plugin to overlay a zip file. Nothing fancy. Here's
the config:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <version>2.5</version>
  <configuration>
    <overlays>
      <groupId>org.company</groupId>
      <artifactId>ui</artifactId>
      <type>zip</type>
    </overlays>
  </configuration>
</plugin>

I get an exception:
java.lang.ClassCastException: java.lang.String cannot be
cast to org.apache.maven.plugin.war.Overlay
at
org.apache.maven.plugin.war.overlay.OverlayManager.initialize(OverlayManager.java:122)

I looked at the WAR source. I don't know how a String is making it into the
List<Overlay> collection. Any WAR developers here?

Cheers,
Paul