CharSequence trimTrailingPadding(CharSequence chars) {
    return checkNotNull(chars);
  }

  // Modified encoding generators

  /**
   * Returns an encoding that behaves equivalently to this encoding, but omits any padding
   * characters as specified by <a href="http://tools.ietf.org/html/rfc4648#section-3.2">RFC 4648
   * section 3.2</a>, Padding of Encoded Data.
   */
  public abstract BaseEncoding omitPadding();

  /**