docs: public int getResponseCode() throws IOException {
          if (responseCode != -1) {
              return responseCode;
          }
  
          // Make sure we've gotten the headers
          getInputStream();
          String resp = getHeaderField(0);
  
          // should have no leading/trailing LWS
          // expedite the typical case by assuming it has the
          // form "HTTP/1.x <WS> 2XX <mumble>"
          int ind;
  
          try {
              ind = resp.indexOf(' ');
              while (resp.charAt(ind) == ' ') {
                  ind++;
              }
              responseCode = Integer.parseInt(resp.substring(ind, ind + 3));
              responseMessage = resp.substring(ind + 4).trim();
              return responseCode;
          }
          catch (Exception e) {
              return responseCode;
          }
      }