code: public StringBuffer format(Object qty, StringBuffer toAppendTo, FieldPosition pos,
                                              int minDecimals, int... fractionGroups) {
          return format(qty, toAppendTo, pos, minDecimals, boxAsList(fractionGroups));
      }
docs: Formats a bitcoin value as a number and possibly a units indicator and appends the
  resulting text to the given string buffer.  The type of monetary value argument can be
  any one of any of the following classes: {@link Coin},
  {@link Integer}, {@link Long}, {@link BigInteger},
  {@link BigDecimal}.  Numeric types that can represent only an integer are interpreted
  as that number of satoshis.  The value of a {@link BigDecimal} is interpreted as that
  number of bitcoins, rounded to the nearest satoshi as necessary.
  
  @param minDecimals The minimum number of decimal places in the fractional part of the formatted number
  @param fractionGroups The sizes of optional additional fractional decimal-place groups
  @throws IllegalArgumentException if the number of fraction places is negative.