code: public DecimalStyle withDecimalSeparator(char decimalSeparator) {
          if (decimalSeparator == this.decimalSeparator) {
              return this;
          }
          return new DecimalStyle(zeroDigit, positiveSign, negativeSign, decimalSeparator);
      }
docs: Returns a copy of the info with a new character that represents the decimal point.
  <p>
  The character used to represent a decimal point may vary by culture.
  This method specifies the character to use.
  
  @param decimalSeparator  the character for the decimal point
  @return  a copy with a new character that represents the decimal point, not null