Patch to allow the JDK API location to be passed to Ant using -Djdk.api
--- build.xml.orig 2016-06-20 15:06:43 UTC
+++ build.xml
@@ -355,6 +355,7 @@
<include name="**"/>
<exclude name="org/jgrapht/experimental/**"/>
</packageset>
+ <link offline="true" packagelistLoc="${jdk.api}" href="${jdk.api}"/>
</javadoc>
</target>