static Set<Class> classSuperclassesAndInterfaces(Class c) {
  if (c == null) null;
  new HashSet<Class> set;
  classSuperclassesAndInterfaces_find(c, set);
  ret set;
}

svoid classSuperclassesAndInterfaces_find(Class c, Set<Class> set) {
  do {
    if (!set.add(c)) ret;
    for (Class intf : c.getInterfaces())
      classSuperclassesAndInterfaces_find(intf, set);
  } while ((c = c.getSuperclass()) != null);
}

Began life as a copy of #1022198