code: public static Stream<Relationship> coverNodes(Collection<Node> nodes) {
          return nodes.stream()
                  .flatMap(n ->
                          StreamSupport.stream(n.getRelationships(Direction.OUTGOING)
                                  .spliterator(),false)
                                  .filter(r -> nodes.contains(r.getEndNode())));
      }
docs: non-parallelized utility method for use by other procedures