manifest attribute via parameter

[Steffen Euch]

Hi!

I'm using this generic target to jar my modules.

<target name="genericJar">
   <jar jarfile="${DEPLOY_DIR}/${generic.jar-name}"
        whenempty="fail"
        manifest="${generic.manifest}">
     <fileset dir="${PRJ_CLASSES}">
         <patternset refid="${generic.patternset}"/>
     </fileset>
   </jar>
</target>

It seems to me, that with it every modul *must* use a manifest file 
(which is delivered by the paramater 'generic.manifest').
But I want to use this target for modules without a manifest file, too.
I've tried to omit the parameter or set it to "" but that doesn't work.

Is it possible to use only one target for both purposes, or must I 
write a second target without the manifest attribute?

Thanks in advance,

Steffen