@GwtIncompatible // serialization
    Object writeReplace() {
      return super.writeReplace();
    }
  }

  ImmutableMap() {}

  /**
   * Guaranteed to throw an exception and leave the map unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  @CheckForNull
  public final V remove(@CheckForNull Object o) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the map unmodified.