code: static String toNumeral(
          NumberSystem numsys,
          char zeroDigit,
          int number
      ) {
  
          if (numsys.isDecimal()) {
              int delta = zeroDigit - '0';
              String standard = Integer.toString(number);
  
              if (delta == 0) {
                  return standard;
              }
  
              StringBuilder numeral = new StringBuilder();
  
              for (int i = 0, n = standard.length(); i < n; i++) {
                  int codepoint = standard.charAt(i) + delta;
                  numeral.append((char) codepoint);
              }
  
              return numeral.toString();
          } else {
              return numsys.toNumeral(number);
          }
  
      }
docs: also called by EastAsianME