Modeling Project Releng/Building/Using Ant-Contrib
From Eclipsepedia
To add ant-contrib to your buildAll.xml, use this:
...
<property file="${buildConfigFile}" />
<taskdef resource="net/sf/antcontrib/antlib.xml">
<classpath>
<pathelement path="${classpath}" />
<pathelement location="${thirdPartyJarsDir}/ant-contrib.jar" />
<fileset dir="/usr/share/java">
<include name="**/ant-contrib*.jar" />
</fileset>
</classpath>
</taskdef>
...