@Override
  public boolean equalsByReference(@NotNull KeyFMap other) {
    if (other == this) {
      return true;
    }
    if (!(other instanceof MapBackedFMap) || other.size() != size()) {
      return false;
    }

    MapBackedFMap map = (MapBackedFMap)other;
    ObjectIterator<Entry<Object>> iterator = int2ObjectEntrySet().fastIterator();
    while (iterator.hasNext()) {
      Entry<Object> next = iterator.next();
      if (map.get(next.getIntKey()) != next.getValue()) {
        return false;
      }
    }
    return true;
  }
@Override
  public boolean equalsByReference(@NotNull KeyFMap other)