docs: public void addHttpSenderListener(HttpSenderListener httpSenderListener) {
          if (httpSenderListener == null) {
              throw new IllegalArgumentException("Parameter httpSenderListener must not be null.");
          }
  
          if (httpSenderListeners == null) {
              httpSenderListeners = new ArrayList<>();
          }
          httpSenderListeners.add(httpSenderListener);
      }