code: public static BtcFormat getInstance(int scale, Locale locale, int minDecimals, int... groups) {
          return getInstance(scale, locale, minDecimals, boxAsList(groups));
      }
docs: Return a new fixed-denomination formatter for the given locale, with the specified
  fractional decimal placing.  The first argument specifies the denomination as the size
  of the shift from coin-denomination in increasingly-precise decimal places.  The third
  parameter is the minimum number of fractional decimal places to use, followed by
  optional repeating integer parameters each specifying the size of an additional group of
  fractional decimal places to use as necessary to avoid rounding, down to a maximum
  precision of satoshis.