ProjectionMap loadaProjectionMap = loada.getProjectionMap();
assertTrue(loadaProjectionMap.changes() == false);
LOLoad loadb = (LOLoad) lp.getRoots().get(1);
ProjectionMap loadbProjectionMap = loadb.getProjectionMap();
assertTrue(loadbProjectionMap.changes() == false);
//check cogroup projection map
LOCogroup cogroup = (LOCogroup)lp.getSuccessors(loada).get(0);
ProjectionMap cogroupProjectionMap = cogroup.getProjectionMap();
assertTrue(cogroupProjectionMap.changes() == true);