code: public StringBuffer format(long number, StringBuffer toAppendTo,
                                 FieldPosition status) {
          return format((double)number, toAppendTo, status);
      }
docs: Specialization of format. This method really calls
  <code>format(double, StringBuffer, FieldPosition)</code>
  thus the range of longs that are supported is only equal to
  the range that can be stored by double. This will never be
  a practical limitation.