<project default="build-whole-jar">
  
  <property name="dest.dir" value="build/lib"/>
  <property name="source.dir" value="build/delivery/classes"/>
  <property name="includes.pattern" value="**/*"/>
  <property name="jarfile.name" value="${APP}.jar"/>

  <target name="init-build-whole-jar">
    <mkdir dir="${dest.dir}"/>
    <available file="_lib" property="exists.lib"/>
  </target>
  
  <target name="copy-libs" depends="init-build-whole-jar" if="exists.lib">
    <copy todir="${dest.dir}" filtering="off" overwrite="true">
      <fileset dir="_lib">
        <include name="*.jar"/>
      </fileset>
    </copy>
  </target>
  
  <target name='build-whole-jar'>
    <antcall target="copy-libs"/>
    <jar jarfile="${dest.dir}/${jarfile.name}" includes="${includes.pattern}" basedir="${source.dir}"/>
  </target>

</project>