}

  public void testBase64CannotLowerCase() {
    assertThrows(IllegalStateException.class, () -> base64().lowerCase());
  }

  public void testBase64CannotIgnoreCase() {
    assertThrows(IllegalStateException.class, () -> base64().ignoreCase());
  }

  public void testBase64AlternatePadding() {
    BaseEncoding enc = base64().withPadChar('~');