result.putAll(multimap);
    return result;
  }

  private interface ValueSetLink<K extends @Nullable Object, V extends @Nullable Object> {
    ValueSetLink<K, V> getPredecessorInValueSet();

    ValueSetLink<K, V> getSuccessorInValueSet();

    void setPredecessorInValueSet(ValueSetLink<K, V> entry);

    void setSuccessorInValueSet(ValueSetLink<K, V> entry);
  }