ifclass MultiMap
static <A> L<A> lookupPossiblyIgnoreCase(MultiMap<S, A> map, S key) {
  if (map == null) null;
  L<A> value = map.get(key);
  ret !value.isEmpty() ? value : lookupIgnoreCase(map, key);
}
endif

static <A> A lookupPossiblyIgnoreCase(Map<S, A> map, S key) {
  if (map == null) null;
  A value = map.get(key);
  ret value != null ? value : lookupIgnoreCase(map, key);
}

Began life as a copy of #1001995