private final ExistingLinksDisplayer existingLinkDisplayer;
public DropdownLinkKeysDefiner(TableRelationship r) {
relation = r;
displayOrderSelector = new ColumnDisplayOrderSelector();
linkDefiner = new LinkDefiner(r.getParentObject(), r.getChildObject(), displayOrderSelector.getSelectedOrder());
links = Sets.newLinkedHashSet(r.getFieldRelationships());
existingLinkDisplayer = new ExistingLinksDisplayer();
existingLinkDisplayer.update();
displayOrderSelector.setCallback(new Receiver<ColumnDisplayOrder>() {