code: @Override
  	public String getString(final FieldCase c) {
  		boolean success = false;
  		String numberString;
  		do {
  			double number = getDouble(c);
  			numberString = format.format(number);
  			if (notZero && ZERO_PATTERN.matcher(numberString).matches()) {
  				log.info(XMLTags.NOTZERO + " is true and a zero value was generated: value=" + numberString + " - generating new value");
  			} else {
  				success = true;
  			}
  
  		} while (!success);
  		if (c.isBad()) {
  			numberString = expression.negateString(numberString, c.getBad());
  		}
  		return numberString;
  	}
docs: If {@link FieldCase#isBad()} is {@code true}, an invalid number is generated using
  {@link GeneratingExpression#negateString(String, int)}
  
  @return a character string representing a random number subject to the FieldCase