code: public String format(Object qty, int minDecimals, int... fractionGroups) {
          return format(qty, new StringBuffer(), new FieldPosition(0), minDecimals, boxAsList(fractionGroups)).toString();
      }
docs: Formats a bitcoin value as a number and possibly a units indicator to a
  {@link String}.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.