Can't find com.bea.control.assembly.AssembleTask

I exported a set of Workshop Ant build scripts for my EAR, WAR and JAR projects.
 I'm trying do do a simple build of the entire EAR by right-clicking on the
build.xml file and running as an Ant Build (using the 'archive' target).

The build fails when it can't execute the <assemble> task in the WAR
project [that the EAR project references] because Ant can't find the
com.bea.control.assembly.AssembleTask class.

I have searched high and low and cannot find a JAR file that contains this (in
my entire WebLogic Platform 9.2.2 installation).

Can someone please tell me where this class is located?

Thanks,