throw new InvalidObjectException("Use SerializationProxy");
  }

  /**
   * The actual object that gets serialized. Unfortunately, readResolve() doesn't get called when a
   * circular dependency is present, so the proxy must be able to behave as the map itself.
   */
  abstract static class AbstractSerializationProxy<K, V> extends ForwardingConcurrentMap<K, V>

    throw new InvalidObjectException("Use SerializationProxy");
  }

  /**
   * The actual object that gets serialized. Unfortunately, readResolve() doesn't get called when a
   * circular dependency is present, so the proxy must be able to behave as the map itself.
   */
  abstract static class AbstractSerializationProxy<K, V> extends ForwardingConcurrentMap<K, V>

    protected String doBackward(Float value) {
      return value.toString();
    }

    @Override
    public String toString() {
      return "Floats.stringConverter()";
    }

    private Object readResolve() {
      return INSTANCE;
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 1;
  }

  /**

   * upon deserialization. An instance of this class is fit for use by the writeReplace of
   * LocalManualCache.
   *
   * <p>Unfortunately, readResolve() doesn't get called when a circular dependency is present, so
   * the proxy must be able to behave as the cache itself.
   */
  private static class ManualSerializationProxy<K, V> extends ForwardingCache<K, V>

    protected String doBackward(Double value) {
      return value.toString();
    }

    @Override
    public String toString() {
      return "Doubles.stringConverter()";
    }

    private Object readResolve() {
      return INSTANCE;
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 1;
  }

  /**