code: public static synchronized void stopAllUploads() {
          if (uploadTasksMap.isEmpty()) {
              return;
          }
  
          // using iterator instead for each loop, because it's faster on Android
          Iterator<String> iterator = uploadTasksMap.keySet().iterator();
  
          while (iterator.hasNext()) {
              UploadTask taskToCancel = uploadTasksMap.get(iterator.next());
              taskToCancel.cancel();
          }
      }
docs: Stop all the active uploads.