docs: protected static void prefixUnitsIndicator(DecimalFormat numberFormat, int scale) {
          checkState(Thread.holdsLock(numberFormat)); // make sure caller intends to reset before changing
          DecimalFormatSymbols fs = numberFormat.getDecimalFormatSymbols();
          setSymbolAndCode(numberFormat,
              prefixSymbol(fs.getCurrencySymbol(), scale), prefixCode(fs.getInternationalCurrencySymbol(), scale)
          );
      }