Vector<Resource> validStarts = new Vector<Resource>();
if (grouping.hasPrimaries()) {
Iterator<ISelector> primariesIt = grouping.getPrimaries().iterator();
while (primariesIt.hasNext()) {
ISelector primary = primariesIt.next();
if (primary.canSelectResources()) {
try {
Iterator<Resource> valids = primary.selectResources(in);
while (valids.hasNext()) {
validStarts.add(valids.next());
}