label = null; // no master/slave. pointless to talk about nodes
if (label != null) {
Set<Node> nodes = label.getNodes();
if (label.isOffline()) {
if (nodes.size() != 1) return new BecauseLabelIsOffline(label);
else return new BecauseNodeIsOffline(nodes.iterator().next());
} else {
if (nodes.size() != 1) return new BecauseLabelIsBusy(label);
else return new BecauseNodeIsBusy(nodes.iterator().next());
}