docs: public MonetaryFormat codeSeparator(char codeSeparator) {
          checkArgument(!Character.isDigit(codeSeparator));
          checkArgument(codeSeparator > 0);
          if (codeSeparator == this.codeSeparator)
              return this;
          else
              return new MonetaryFormat(negativeSign, positiveSign, zeroDigit, decimalMark, minDecimals, decimalGroups,
                      shift, roundingMode, codes, codeSeparator, codePrefixed);
      }