code: public static AcceptDatetime valueOf(final String value) {
          if (value != null) {
              final Instant time = parseDatetime(value);
              if (time != null) {
                  return new AcceptDatetime(time);
              }
          }
          return null;
      }
docs: Create an Accept-Datetime header object from a string.
  
  @param value the header value
  @return an AcceptDatetime object or null if the value is not parseable