code: private void parseIDFromCookies(RequestMessage request) {
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "Looking for ID in cookies");
          }
          Enumeration<String> list = request.getHeaders("Cookie");
          while (list.hasMoreElements()) {
              String item = list.nextElement();
              int index = item.indexOf(getSessionConfig().getIDName());
              if (-1 != index) {
                  index = item.indexOf('=', index);
                  if (-1 != index) {
                      index++;
                      // TODO this is assuming that the full value is valid and
                      // grabbing just the 4 digit id...
                      if (item.length() >= (index + 4)) {
                          this.id = item.substring(index, index + 4);
                          this.fromCookie = true;
                          break;
                      }
                  }
              }
          }
      }
docs: Look for a possible session id in the cookies of the request message.
  
  @param request