Turn on jar index creation. Classworlds may end up using this at some point. Only a small increase in the size of jars.

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-1/plugins/trunk@113264 13f79535-47bb-0310-9956-ffa450edef68

jar/plugin.jelly

@@ -29,6 +29,7 @@
     <ant:jar
       jarfile="${maven.build.dir}/${maven.final.name}.jar"
       basedir="${maven.build.dest}"
+      index="true"
       excludes="${maven.jar.excludes}"> 
       
       <j:if test="${maven.jar.manifest.available}">