@Override
    public StringBuffer format(Object qty, StringBuffer toAppendTo, FieldPosition pos) {
        return format(qty, toAppendTo, pos, minimumFractionDigits, decimalGroups);
    }
@ Override public StringBuffer format ( Object qty , StringBuffer toAppendTo , FieldPosition pos ) { return format ( qty , toAppendTo , pos , minimumFractionDigits , decimalGroups ) ; }
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.

@return the {@link StringBuffer} passed in as {@code toAppendTo}