if ((e1 instanceof AlertScanNode) && (e2 instanceof AlertScanNode)) {
return compareAlertNodes((AlertScanNode) e1, (AlertScanNode) e2);
} else if ((e1 instanceof AlertSeverityNode)
&& (e2 instanceof AlertSeverityNode)) {
final AlertSeverityNode asn1 = (AlertSeverityNode) e1;
final AlertSeverityNode asn2 = (AlertSeverityNode) e2;
return asn2.getSeverityIndex() - asn1.getSeverityIndex();
} else {
return super.compare(viewer, e1, e2);
}
}