code: public static TokenRequest create(FullHttpRequest httpRequest) {
          if (httpRequest.headers() != null && httpRequest.headers().get(HttpHeaderNames.CONTENT_TYPE) != null
                  && httpRequest.headers().get(HttpHeaderNames.CONTENT_TYPE).contains(HttpHeaderValues.APPLICATION_X_WWW_FORM_URLENCODED)) {
              return new TokenRequest_x_www_form_urlencoded(httpRequest);
          } else {
              return TokenRequest_json.create(httpRequest);
          }
      }
docs: 工厂方法,支持的contentType有application/x-www-form-urlencoded,application/json(默认)