// Combine relations if possible.
relations = GTTools.getChildren(host, false, false, false, true);
for (Object relationObject : relations) {
Relation relation = (Relation) relationObject;
List<?> vertices = relation.attributeList(Vertex.class);
if (vertices.isEmpty()) {
List<?> linkedObjects = relation.linkedObjectsList();
if (linkedObjects.size() == 2) {
NamedObj head = (NamedObj) linkedObjects.get(0);
NamedObj tail = (NamedObj) linkedObjects.get(1);