code: @Nonnull
    @ReturnsMutableCopy
    public static byte [] decode (@Nonnull final byte [] source, final int options) throws IOException
    {
      return decode (source, 0, source.length, options);
    }
docs: Low-level access to decoding ASCII characters in the form of a byte array.
  <strong>Ignores GUNZIP option, if it's set.</strong> This is not generally
  a recommended method, although it is used internally as part of the
  decoding process. Special case: if len = 0, an empty array is returned.
  Still, if you need more speed and reduced memory footprint (and aren't
  gzipping), consider this method.
  
  @param source
  The Base64 encoded data
  @param options
  Can specify options such as alphabet type to use
  @return decoded data
  @throws IOException
  In case of error
  @since 2.3.1