static L mapAndRecordToMap_reversed(Map recordMap, Iterable l, O f) {
  ret mapAndRecordToMap_reversed(recordMap, f, l);
}

static L mapAndRecordToMap_reversed(Map recordMap, O f, Iterable l) {
  L x = emptyList(l);
  if (l != null) for (O o : l) {
    O b = callF(f, o);
    if (recordMap != null) recordMap.put(b, o);
    x.add(b);
  }
  ret x;
}

Began life as a copy of #1015378