Import of relative dir in JAR is not working

When you try to import a dir relative to the group file which and everything is loaded from a JAR, you get an NPE when closing the InputStream at org.stringtemplate.v4.misc.Misc.urlExists(URL). This is a problem with the JDK, the same problem is described here: https://jira.springsource.org/browse/SPR-1629
My solution here is to put the close of the InputStream into a new finally block, swallowing all relevant  exceptions.