HPCC-10186 Better Java Support for JAR Files and the ClassPath

Fix the url classpath.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5461 from richardkchapman/java-classpath-fixes

HPCC-10186 Better Java Support for JAR Files and the ClassPath

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>