The findResources method is supposed to enumerate all the class path
elements' matching paths' URLs, but we used to stop at the first one.
While this is good enough when the system class path contains only a
single .jar file, since b88438d2(sketch of JAR support in Finder)
supports more than a single .jar file in the class path.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>