Major Description
The Java Broker implements two URL Stream Handlers:data: and classpath:. It registers these with the JVM using the java.protocol.handler.pkgs system property. Unfortunately, this technique only works if the Broker's JARs are loaded by the JVM's System classloader. If the Broker is loaded by a child classloader (as might be the case if the Broker is embedded within a container, a maven plugin or testing framework) this technique fails.
There seem to be a few (ugly) workaround for this problem documented on-line, but I have not evaluated merits.