code: private Collection<Node> collectPersistenceXml(final Archive<?> archive) {
          final Collection<Node> nodes = new LinkedList<Node>(getPersistenceDescriptors(archive));
          for (Node node : collectSubArchives(archive)) {
              if (node.getAsset() instanceof ArchiveAsset) {
                  final ArchiveAsset archiveAsset = (ArchiveAsset) node.getAsset();
                  nodes.addAll(collectPersistenceXml(archiveAsset.getArchive()));
              }
          }
          return nodes;
      }
docs: Recursively scans archive content (including sub archives) for persistence.xml descriptors.