bundles/org.eclipse.build.tools/plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.0"?>
<plugin>

    <extension
         point="org.eclipse.ant.core.extraClasspathEntries">
      <extraClasspathEntry
            library="buildTools.jar">
      </extraClasspathEntry>
   </extension>
	<!-- Tasks -->
   <extension point="org.eclipse.ant.core.antTasks">


      <antTask
            library="buildTools.jar"
            name="unpackUpdateJars"
            class="org.eclipse.releng.UnpackUpdateJars">
      </antTask>

    </extension>
</plugin>