code: public static boolean isAcceptRange(int responseCode, FileDownloadConnection connection) {
          if (responseCode == HttpURLConnection.HTTP_PARTIAL
                  || responseCode == FileDownloadConnection.RESPONSE_CODE_FROM_OFFSET) return true;
  
          final String acceptRanges = connection.getResponseHeaderField("Accept-Ranges");
          return "bytes".equals(acceptRanges);
      }
docs: accept range is effect by  response code and Accept-Ranges header field.