* operations will work correctly. To allow concurrent update operations, wrap your multimap with a
 * call to {@link Multimaps#synchronizedMultimap}.
 *
 * <p>For serialization to work, the subclass must specify explicit {@code readObject} and {@code
 * writeObject} methods.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible

   * according to spec.
   *
   * <p>This ordering is not serializable, as its implementation relies on {@link
   * System#identityHashCode(Object)}, so its behavior cannot be preserved across serialization.
   *
   * @since 2.0
   */
  // TODO(kevinb): copy to Comparators, etc.
  @J2ktIncompatible // MapMaker
  public static Ordering<@Nullable Object> arbitrary() {

* `datetime.timedelta`:
    * 파이썬의 `datetime.timedelta`.
    * 요청과 응답에서 전체 초(seconds)의 `float`로 표현됩니다.
    * Pydantic은 "ISO 8601 time diff encoding"으로 표현하는 것 또한 허용합니다. [더 많은 정보는 문서를 확인하세요](https://docs.pydantic.dev/latest/concepts/serialization/#custom-serializers).
* `frozenset`:
    * 요청과 응답에서 `set`와 동일하게 취급됩니다:
        * 요청 시, 리스트를 읽어 중복을 제거하고 `set`로 변환합니다.
        * 응답 시, `set`는 `list`로 변환됩니다.

* Protobuf serialization does not distinguish between `[]` and `null`.
API fields previously capable of storing and returning either `[]` and `null` via JSON API requests (for example, the Endpoints `subsets` field)
can now store only `null` when created using the protobuf content-type or stored in etcd using protobuf serialization (the default in 1.6).

      Object key = e.getKey();
      return key != null && LocalCache.this.remove(key, e.getValue());
    }
  }

  // Serialization Support

  /**
   * Serializes the configuration of a LocalCache, reconstituting it as a Cache using CacheBuilder
   * upon deserialization. An instance of this class is fit for use by the writeReplace of
   * LocalManualCache.
   *

* `datetime.timedelta`:
    * Pythonの`datetime.timedelta`です。
    * リクエストとレスポンスでは合計秒数の`float`で表現されます。
    * Pydanticでは「ISO 8601 time diff encoding」として表現することも可能です。[詳細はドキュメントを参照してください](https://docs.pydantic.dev/latest/concepts/serialization/#custom-serializers)。
* `frozenset`:
    * リクエストとレスポンスでは`set`と同じように扱われます:
        * リクエストでは、リストが読み込まれ、重複を排除して`set`に変換されます。
        * レスポンスでは`set`が`list`に変換されます。

  @Override
  public int hashCode() {
    return runtimeType.hashCode();
  }

  @Override
  public String toString() {
    return Types.toString(runtimeType);
  }

  /** Implemented to support serialization of subclasses. */
  protected Object writeReplace() {
    // TypeResolver just transforms the type to our own impls that are Serializable
    // except TypeVariable.

    stream.defaultWriteObject();
    Serialization.writeMap(this, stream);
  }

  @GwtIncompatible
  @J2ktIncompatible
    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    int size = stream.readInt();
    init(16); // resist hostile attempts to allocate gratuitous heap
    Serialization.populateMap(this, stream, size);
  }

Üstelik tüm avantajlarla birlikte:

* Editör desteği (her yerde tamamlama!)
* Veri dönüştürme (diğer adıyla parsing / serialization)
* Veri doğrulama (validation)
* Schema dokümantasyonu

    // No equals and hashCode; see ForwardingObject for details.

    @Override
    public String toString() {
      synchronized (mutex) {
        return delegate.toString();
      }
    }

    // Serialization invokes writeObject only when it's private.
    // The SynchronizedObject subclasses don't need a writeObject method since
    // they don't contain any non-transient member variables, while the