Ant parallel task for signjar

Question

im trying to run the ant task to run parallely under list of folders. But this isnt working. The below Code throws me "jar must be set through jar attribute or nested filesets". I tried various options for parallel but no success. Appreciate help

                    <for list="fold1,fold2,fold3,fold4" param="letter" parallel="true">
                            <sequential>
                                    <fileset dir="${my.libdir}">
                                    <include name="@{letter}/*.jar"/>
                                    </fileset>
                                    <signjar alias="${alias}" keystore="${keystore}" storepass="${storepass}" lazy="true">
                                    </signjar>
                            </sequential>
                    </for>

Answer 1

The below Code solved my issue. Hope it helps someone in need

<for param="file" parallel="true">
<path>  
<fileset dir="${mylibdir}" includes="**/*.jar">
<exclude name="build/*.jar"/>
<exclude name="nosign/*.jar"/>
<exclude name="test/*.jar"/>
<exclude name="docs/*.jar"/> 
</fileset>
</path>
<sequential>
<signjar jar="@{file}" alias="${alias}" keystore="${keystore}"   storepass="${storepass}" lazy="true" tsaurl="<url of timestamping authority>" />
</sequential>
</for>