code: public static String getRandomNumber(int numberLength, boolean paddingOn) {
          if (numberLength < 1) {
              throw new InvalidFunctionUsageException("numberLength must be greater than 0 - supplied " + numberLength);
          }
  
          StringBuilder buffer = new StringBuilder();
          for (int i = 0; i < numberLength; i++) {
              buffer.append(generator.nextInt(10));
          }
  
          return checkLeadingZeros(buffer.toString(), paddingOn);
      }
docs: Static number generator method.
  @param numberLength
  @param paddingOn
  @return