docs: private static DateTimeFormatter createFormatterForStyleIndex(int dateStyle, int timeStyle) {
          int index = ((dateStyle << 2) + dateStyle) + timeStyle;  // (dateStyle * 5 + timeStyle);
          // Should never happen but do a double check...
          if (index >= cStyleCache.length()) {
              return createDateTimeFormatter(dateStyle, timeStyle);
          }
          DateTimeFormatter f = cStyleCache.get(index);
          if (f == null) {
              f = createDateTimeFormatter(dateStyle, timeStyle);
              if (cStyleCache.compareAndSet(index, null, f) == false) {
                  f = cStyleCache.get(index);
              }
          }
          return f;
      }