for (String iterID : new HashSet<String>(iterationIds.values())) {
CoLocationGroup ccg = new CoLocationGroup();
AbstractJobVertex tail = streamVertices.get(iterationIDtoTailName.get(iterID));
AbstractJobVertex head = streamVertices.get(iterationIDtoHeadName.get(iterID));
ccg.addVertex(head);
ccg.addVertex(tail);
}
}
/**