When using the ZipExporter to create a file representation of an archive it doesn't create the needed directory entries:

/META-INF/MANIFEST.MF
/org/jboss/test/MyClass.class

should be

/META-INF
/org
/org/jboss
/org/jboss/test
/META-INF/MANIFEST.MF
/org/jboss/test/MyClass.class

Note that the directory entries should be sorted such that any tools extracting such a file can depend on parent directories being there.