docs: private static boolean isNumericToken(String token) {
          int tokenLen = token.length();
          if (tokenLen > 0) {
              char c = token.charAt(0);
              switch (c) {
              case 'c': // century (number)
              case 'C': // century of era (number)
              case 'x': // weekyear (number)
              case 'y': // year (number)
              case 'Y': // year of era (number)
              case 'd': // day of month (number)
              case 'h': // hour of day (number, 1..12)
              case 'H': // hour of day (number, 0..23)
              case 'm': // minute of hour (number)
              case 's': // second of minute (number)
              case 'S': // fraction of second (number)
              case 'e': // day of week (number)
              case 'D': // day of year (number)
              case 'F': // day of week in month (number)
              case 'w': // week of year (number)
              case 'W': // week of month (number)
              case 'k': // hour of day (1..24)
              case 'K': // hour of day (0..11)
                  return true;
              case 'M': // month of year (text and number)
                  if (tokenLen <= 2) {
                      return true;
                  }
              }
          }
              
          return false;
      }