UMLGeneralizationEnumeration exts = classifier.getGeneralizations();
UMLGeneralization generalization;
UMLGeneralizableElement zuper;
String zuperName;
while (exts.hasMoreElements()) {
generalization = exts.getNextUMLGeneralization();
zuper = generalization.getSupertype();
zuperName = zuper.getQualifiedName();
error(category + " " + classifier.getQualifiedName() + " cannot extend " + zuperName);
}