docs: @Override
      public AttributedCharacterIterator formatToCharacterIterator(Object obj) { synchronized(numberFormat) {
          DecimalFormatSymbols anteSigns = numberFormat.getDecimalFormatSymbols();
          BigDecimal units = denominateAndRound(inSatoshis(obj), minimumFractionDigits, decimalGroups);
          List<Integer> anteDigits = setFormatterDigits(numberFormat, units.scale(), units.scale());
          AttributedCharacterIterator i = numberFormat.formatToCharacterIterator(units);
          numberFormat.setDecimalFormatSymbols(anteSigns);
          setFormatterDigits(numberFormat, anteDigits.get(0), anteDigits.get(1));
          return i;
      }}