build.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project default="jar" name="Create Jar for Postgres Functions">
    <property name="debuglevel" value="source,lines,vars"/>
    <property name="target" value="1.7"/>
    <property name="source" value="1.7"/>

  <target name="jar">
      <property name="libraryname" value="./pg_combined.jar"/>
        <jar destfile="${libraryname}" filesetmanifest="mergewithoutmain" duplicate="preserve">
            <manifest>
                <attribute name="Class-Path" value="."/>
            </manifest>
            <fileset dir="build" includes="**/*.class" />
            <!-- <zipgroupfileset dir="lib" includes="*.jar"/> -->
        </jar>
        <tempfile property="templib" destdir="."/>
        <move tofile="${templib}" file="${libraryname}"/>
        <zip file="${libraryname}">
          <zipfileset src="${templib}">
            <exclude name="META-INF/**"/>
          </zipfileset>
        </zip>
        <delete file="${templib}" quiet="true"/>
    </target>
</project>