static <A, B, C> Map<A, C> mapValues_withoutNulls(Map<A, B> map, IF1<B, C> f) {
  ret mapValues_withoutNulls(f, map);
}

static <A, B, C> Map<A, C> lambdaMapLike mapValues_withoutNulls(IF1<B, C> f, Map<A, B> map) {
  Map m = similarEmptyMap(map);
  for (A key, B val : map) {
    O v = f.get(val);
    if (v != null)
      m.put(key, v);
  }
  ret m;
}

Began life as a copy of #1004652