code: @Nullable
    public static OffsetDateTime getDateTimeFromW3C (@Nullable final String sDate)
    {
      if (StringHelper.hasNoText (sDate))
        return null;
  
      return parseOffsetDateTimeUsingMask (W3CDATETIME_MASKS, sDate.trim ());
    }
docs: Parses a Date out of a String with a date in W3C date-time format. <br>
  It parsers the following formats:
  <ul>
  <li>"uuuu-MM-dd'T'HH:mm:ssz"</li>
  <li>"uuuu-MM-dd'T'HH:mmz"</li>
  <li>"uuuu-MM-dd"</li>
  <li>"uuuu-MM"</li>
  <li>"uuuu"</li>
  </ul>
  <p>
  Refer to the java.text.SimpleDateFormat javadocs for details on the format
  of each element.
  </p>
  
  @param sDate
  string to parse for a date. May be <code>null</code>.
  @return the Date represented by the given W3C date-time string. It returns
  <b>null</b> if it was not possible to parse the given string into a
  {@link ZonedDateTime} or if the input string was <code>null</code>.