code: public static HttpVersion valueOf(String text) {
          if (text == null) {
              throw new NullPointerException("text");
          }
  
          text = text.trim().toUpperCase();
          if ("RTSP/1.0".equals(text)) {
              return RTSP_1_0;
          }
  
          return new HttpVersion(text, true);
      }
docs: Returns an existing or new {@link HttpVersion} instance which matches to
  the specified RTSP version string.  If the specified {@code text} is
  equal to {@code "RTSP/1.0"}, {@link #RTSP_1_0} will be returned.
  Otherwise, a new {@link HttpVersion} instance will be returned.