code: public static void saveAsync(String key, Object object, SaveToCacheCallback callback) {
          new SaveTask(key, object, callback).execute();
      }
docs: Put an object into Reservoir with the given key asynchronously. Previously
  stored object with the same
  key (if any) will be overwritten.
  
  @param key      the key string.
  @param object   the object to be stored.
  @param callback a callback of type {@link quickutils.core.cache.interfaces.SaveToCacheCallback
  .ReservoirPutCallback} which is called upon completion.