add external jar file while building project
<target name="-post-jar">
<jar jarfile="dist/Combined-dist.jar">
<zipfileset src="${dist.jar}" excludes="META-INF/*" />
<zipfileset src="lib/commons-io-1.4.jar" excludes="META-INF/*" />
<zipfileset src="lib/ninja-utils-3.2.jar" excludes="META-INF/*" />
<zipfileset src="lib/unicorn-1.0.jar" excludes="META-INF/*" />
<manifest>
<attribute name="Main-Class" value="com.example.mypackage.Main"/>
</manifest>
</jar>
</target>